Assuming you own the computer you're reading this post on, several of the major ebook vendors have desktop apps you can use to read their stuff. (angelahighland.com)
If that means one of the other ebook vendors, go for it! (angelahighland.com)
For an overview of ebook vendors (many of which also sell print books) and how to distribute to them, check out our blog post here. (mybookcave.com)