I greatly enjoy reading and thinking about evolution.
Here's an interesting article about Charles Darwin exposing some common fallacies (some of them I thought were true). To date I've only finished reading the Voyage of the Beagle but in my experience you get a much greater understanding of things when you go to the source. If you want a real eye-opening experience (besides reading the works of Darwin or Ernst Mayr of course) check out the
TalkOrigins archive.