If you're not sure where to look for what, perhaps this can help:
If you're interested in J.R.R Tolkien's Lord of the Rings, or fantasy in general check out the lyrics of Rivendell in the album Fly By Night and The Necromancer in Caress Of Steel. If you're inclined towards science fiction, and futuristic politics, check out 2112. Greek Mythology makes an appearance in Hemispheres and the concept of Freewill is written about in Permanent Waves. Those interested in travel, and in particular London and New York should definitely check out The Camera Eye in one of their best selling albums of all time Moving Pictures. Suburban life is dealth with in Subdivisions, Hemingway in Losing it, and the space shuttle Columbia in Countdown ,in the album Signals, probably the album with the strangest cover of all. There is something for everyone in the rest of the albums and lyrics.
If you haven't heard any RUSH yet, what are you waiting for?