SailorVGame.Org :: A constantly updated hub of information + downloads for Sailor Moon games. Anything you need can be found here for free. The 'site has exploded since its humble beginnings as just a port for the fan-made Sailor V video game, and it's sure to just keep on growing.
:: The Super Senshi Playground, or Sai-Ga (Sailor Games), is a great resource for popular ROMs and, most especially, KiSS Dolls + games made by the 'Site's creator, like puzzles + JavaScript games (which are lots of fun). The website also offers colouring pages, Oekaki boards, the 'Destiny's Revival' fan-Game Series + discussion forums. Have a ball!
:: This isn't exactly a game website, but it's certainly lots of fun. Tsukuttemiyou! is a website dedicated to the very rarely-known Sailor Moon Sailor Stars game 'Tsukuttemiyou yo! Bishoujo Senshi Sailor Moon' which features a lot of different crafts you can print off your computer and videos about how to turn them into brilliant 3D sailor moon toys. The videos and the kits themselves are up for free download, so you should definitely pay a visit and have a blast.
TvLiveShows - Sailor Moon :: TvLiveShow's Sailor Moon section has all 200 episodes in Japanese with English subtitles that you can watch streaming online. No need to take up precious space on your harddrive. I've tried the first episode and it works just great, although I'm not sure if there will be bugs in later episodes. The website is hosted by Zango which prompts you to download something but you can avoid that just by clicking 'Cancel'. It won't redirect you from the page if you do so. Currently the movies aren't online, though. If it's the Dub you want then most it can be watched online at the Sailor Moon Center.
:: Himura-Kaoru.com, your #1 stop for direct downloads of the Anime, Live Action and even the Dub. They're in RealMedia format so you can't use them for things like Music Videos without converting them first, and you'll need a RealMedia player to watch them. The Subtitles are ADV + VKLL, both infamous for their occasional innacuracy, so take what you read with a pinch of salt and use common sense and prior knowledge in some cases (for example, you should be able to figure out that when Luna says 'MUUN SUTIKKU' she's saying 'Moon Stick', not 'Crescent Moon Wand', and that the last three words of the PGSM opening are 'Moonlight Real Girl' not 'Moonlight Miracle' and that 'GAADIAN' is not the Japanese word for 'probably').
SailorSS :: An old and fairly well-known website that offers the entire Series for download from MegaUpload in .MPG4 format. I find MegaUpload to be too slow for my tastes with such large files, and you still can't use .MPG4 for video editing anyway, so the downloads will still be no good for music videos, and they can only be played in QuickTime. But if .MPG4 formatting makes your toes curl with delight, then this is for you. The one I downloaded as a test didn't work right, but that might just be my computer.
:: Neo Nobility, offering you direct downloads on the Sailor Moon Manga, side-stories and even the ever-entertaining Parallel Sailor Moon joke story. It's the English Manga, so it's legal, since their license has expired.
The Manga of Naoko Takeuchi :: Not a download 'site, but a set of translations. Since the above link is for the English Manga, it's not the most accurate of dialogue; so use these translations to get the whole story.
:: 'Crimson Night', a website that "features a variety of games from online shooters to weird arcade style pinball/maze hybrids", seems like an odd place to be able to download a Scanlation of the entire Sailor V Manga, but there you go. I really do recommend you download it; it's a wonderful, beautiful and hilarious Manga. It actually ties in with the Sailor Moon Metaverse canonically, so it's literally a prequel to the entire Series. And Grand Theft Fansubs makes it even more hilarious without detracting from the storyline.
:: Sera Myu Antics, a huge resource for Myu-flavoured Doujinshi, information + a bunch o' fun stuff, not to mention almost any Omake + Fan Kan you can think of.
Prose 'n' Poetry :: All right, I'll admit it. This 'site is horrible. What started off as a largely Sailor Moon-driven website has degenerated into... um... whatever the heck this is. But it's the only place I know of that offers the Sailor Moon Musicals subtitled, and as Direct Downloads.
Please note; these downloads take a long time. They have been split up into parts, not all of them are available and I think you need to sign up to download them. But regardless of all that the end result is still really good quality, actually, and the Musicals are definitely worth the wait. It's like a combination of all the plotlines smooshed together; and it came before the Live Action, so see the very first real faces of Usagi Tsukino!
Prose-n-Poetry have recently given their Myu section a facelift. The downloads still take a very long time, but you can also watch most of the videos they have available on their website through a player. The layout has been divided into Stages as well so it's easier to navigate.
That being said, with the download rate the way it is, I'm looking for a better source. There is of course The Oracle, but they only have 2 Myu in total (and only 1 you can Download). Still, it's probably faster, so go take a look.
Sailor Moon Doujinshi Library :: Exactly like the title says. Despite the website being relatively new, they offer information on over 150 Doujinshi and have over 100 available for download. Keep checking back to this one because it's just going to get bigger.
Yaoi Doujinshi Downloads - Sailor Moon :: In case you don't know what 'Yaoi' is, it's graphic male x male sex. 'Shounen Ai' means 'boy love' and it's not quite as graphic. There are a lot of fans of these mediums on the Internet. This website offers 'Skin Power' for Download which is the only fully-Yaoi Sailor Moon Doujinshi I know (Nephrite x Jadeite). Download at your own risk.
:: Starlight Pops, a great Starlights Shrine that also has a huge Starlight-themed Doujinshi gallery you can read online (Accompaniment>Other>Doujinshi).
Kotono Mitsuishi Official Site :: The Japanese homepage of the veteran actress who voices Usagi Tsukino/Sailor Moon/Chibi Chibi in the Anime. Also has a blog + downloadable samples of her voice acting. Warning: Exceedingly cute. Also, flash + sounds (well, she is a VA after all).
Sawai Miyuu Official Site :: The official Japanese homepage of popular idol Miyuu Sawai, who played none other than PGSM!Usagi Tsukino. Includes a blog ('My Heart').
:: A Fruitful Spring, a new but comprehensive fan site for Rika Izumi (formerly Chisaki Hama) from the same group as the Ayaka502 Fansite (see below).
KEIKO'S BLOG :: Keiko Kitagawa's Japanese blog. Keiko is the actress for the Live Action Sailor Mars, for the uninformed. There is an excellent up-to-date translation for her entries here.
:: //Itsumo: Keiko Kitagawa\\, or IKK for short, is a definitive Keiko Kitagawa resource + fansite. Aside from regular updates the website offers lots of goodies like image galleries + music downloads from productions she's been involved in.
Mew Mew :: The Japanese blog of Myuu "Mew" Azama, the Japanese actress for Makoto Kino in the Live Action series. As seems to be the trend, there are plenty of pictures to look at even if you aren't familiar with the language.
Ayaka502 :: Official Japanese homepage of Ayaka Komatsu, actress of PGSM!Minako Aino. There is an English version of her blog available here.
:: Ayaka502 Fansite, 'The Ayaka Komatsu Information Center'. Includes a download section of most of her Idol DVDs and lots of fan-created multimedia as well as a large image gallery. Also can be reached through ayakakomatsu.com.
Yoshito Endo Official Site (choose 'Flash site') :: The official Japanese homepage of Endo Yoshito, classical pianist/composer/singer/actor of PGSM!Zoisite. The website recently got a new Flash facelift; though it's much sleeker now, there is a lot less media; there are no longer any songs available for download and there isn't as much information about his acting roles. The main navigation is still in English, though (although sometimes misspelt; 'comming soon', for example), and there is still a playlist of his songs you can listen to for free, so it's not a complete loss. Still worth a look.
Da-!Da-! :: If you speak Japanese, then this is the webblog of Alisa Yuriko Durbrow, who plays Mio Kuroki in the Live Action (a main but PGSM-only villain). Even if you don't speak Japanese, there's a photo with every entry, so it's still fun to look at.
Sailormoon Channel :: Naoko's Sailor Moon website. It's all in Japanese and full of flash + noises, so be pre-warned. This is where I find the Luna's Mailbox to translate each month (click on Luna).
:: Sailor Music, your one-stop location for Sailor Moon music. It has everything, even remixes! The files are .ogg, which is better than .mp3, but you'll need a specific player (I suggest Quintessential Player for Windows or VLC for Mac). If you really can't stand not having .mp3s, then you can download a free + convenient converter here.
:: Manga Style, owned by the same person who owns Sailor Music. Has scans of all the Manga artbooks as well as translations of Naoko Takeuchi's notes and the images from the official Sailor Moon website's updates.
:: The only Sailor Moon forums you'll ever need. Whether it be answers, confirmation, feedback or just laughs, these are your guys.
:: If I were going to make a list of all the Sailor Moon fanlistings, I'd be here all day. So here's the fanlisting for the whole Series. But if fanlistings aren't your thing, then there's a very large rare image gallery in it for you too.
:: If it's information you need, then to Wikimoon you go. That's right, there's a Sailor Moon Wikipedia. Before you feel the need to ask a question in forums, maybe check here first.