On the web besides google, I use wikipedia the most. I have never been a fan of encyclopedias (in book form). I have always thought of them as cumbersome. I like the search and link features of wikipedia (in general any website). This way I can get the information I want quickly and also jump to topics in the presented information immediately.
Today I was looking up on the novel Hyperion by Dan Simmons and ended up on a wild chase on quite a few topics. Here are a few of the topics I checked.
Hyperion the novel
Giant impact hypothesis