E-books

Well, sure enough, I've mislaid my username and password to get onto my own web-site, so I need to get new ones before announcing there about Marked Man and Blood Maidens (though Deb, bless her, has done so...)

But, I have another question (before I start to work today).

I'm taking baby-steps into the 21st Century (it is the 21st, right?), and am contemplating both i-phones and Kindles (or similar readers). Now, my questions are:
a) am I limited to Amazon books for Kindle? Or can I get stuff...