I did no novel-length electronic reading before the Sony Reader, so my catalog is a little smaller than you guys how have been at it for a while on other devices. I've bought 3 books from Baen, just began looking through their catalog about a month ago. If anyone has specific recommendations from their catalog I'd be interested to hear it, currently going through the David Weber books.
Let's see, in my Connect library I currently have:
8 Baen Books (5 "free library", 3 bought)
3 Public domain books
13 Connect books
Plus the free samples that came with the Reader. If I add up my girlfriend's purchases on her laptop (we share a Connect account) we've purchased 24 Connect books.
All books we did not own, but she has been talking about re-buying some books in electronic format when she wants to re-read them.
I read mostly scifi, fantasy and some history with the occassional classic thrown in.