The Wikipedia sample (started in release 12) is a lot of fun! I subscribed to the Wikipedia sample, then went into rss2book's "customize" screen and typed random words and phrases at the end of the URL and hit the "test" button. Boom, a pdf would open with the wikipedia entry, photos and all... The sample's URL is
http://en.wikipedia.org/wiki/nikola_tesla - replace "nikokola_tesla" with "the_clash" or "sony_reader" or "robocop" and hit the "test" button each time. It's like surfing Wikipedia in pdf. Of course, you'll want to save your favorites to the Reader.