I'm also a Kindle owner. I've been using it just over a year now and I've got about 500 books loaded onto it right now. Amazon Customer Service is one of the big selling points on it for me. During the super bowl I dropped my kindle off the end table when it wasn't in it's case and it hit just wrong to break the screen. Even though the 1 year warranty doesn't officially cover drops, Amazon overnighted me a new Kindle with free shipping. Best of all the warranty was expiring 2 days later, but they still exchanged it.
There is a HUGE amount of public domain free and nicely formatted books. Anyone who says you can only use Amazon books on a Kindle hasn't done the research on it. If you want a huge resource on e-readers and books
www.mobileread.com is one of the biggest and best around. It's also one of the places where the author of the Calibre program posts, it has a section on there.
I read a lot of scifi books and Baen is a great publisher of ebooks, all of the ones they sell are DRM free so they can be used on any reader. They have a large amount of freely available books available for download at
http://baencd.thefifthimperium.com/
Speaking of covers for the Kindle I ended up purchasing a cover from Oberon Designs (
http://www.oberondesign.com/ ). They are thick leather that look amazing in person and provide good protection. I picked up the Tree of Life design for my Kindle, but there are a huge amount of them available, they even have them for the Nook now.