Some great places to play trivia on the web: And some places where you can look for the answers:

From all the search engines, I like AltaVista the best. When I started to use it, my results in the Osiris Quiz went from 10 to 20 (on average, from 25 questions).
Sometimes, when you know exactly where to look for the answer, it's quicker to descend in some catalog than to use a search engine. For example, if you need to look at the periodic table you can be sure to find it under Sciences:Chemistry in any decent catalog. I like to use Yahoo.
For many kinds of questions I have found good reference sites that makes the game much easier:

Newsgroup: rec.games.trivia
Read their FAQ first, it has a lot of interesting facts:
The rec.games.trivia Frequently Asked Questions.
And please, oh please, don't ask there about the third english word ending in -gry.


And finally, the queen of all trivia games: "Chto?Gde?Kogda?". Actually, it's much more than just trivia. You can read about it in English on Dmitry Zharkov's page , but that's about all you can do unless you know Russian.
If you know Russian, there are more things to do. One of this days I'll figure out typing in KOI-8, but until then bear with me.