eBook Vendors

I love reading eBooks on the iPhone. i don't even mind bying them, but I am wondering if there are any eBook vendors that don't sell books for a particular ereader or in a certain format (i.e., iBooks or kindle). Are there venders that sell eBooks in epub or pdf? i'd like to keep all my books in one place, instead of spread out across various apps on my phone.

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#1 Free Books!

Hello, Try out Project Gutenberg if you have not discovered it yet... http://osxdaily.com/2012/04/05/load-up-your-ipad-with-a-massive-library-of-over-38000-free-ebooks/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+osxdaily+%28OS+X+Daily%29