There are quite a few online stores that sell DRM free books.
smashwords.com and baenebooks.com are two of my favorites. Both have large free libraries.
But DeDrm (google it) isn’t just for piracy: I am a big believer in supporting authors too. But I use it on anything I buy from Amazon, because everything I own is in my Calibre library in both epub and mobi formats, because I do switch back and forth from time to time.
I buy nothing to download directly to my Kindle. Mostly because of the old screwup: If wifi is on, and I can download books from Amazon to the Kindle, then Amazon can also delete them if they choose. I don’t particularly WANT a bookstore on my reader, I just want it for… um… reading?
