Alexis Harrington is doing her backlist through Smashwords.
Mike Stackpole is doing a couple of his old titles on his website and on Amazon.
Dana Stabenow is doing her Liam Campbell (except for the new one) and Star Svensdotter books through Amazon. They're DRM free which is good, because the one I bought had the worst formatting you can get (no paragraph indents nor with those lacking spaces between the paragraphs).
Which brings up a point. It's great that they can bring out their backlists themselves and basically get all the money for their work, but in many cases I think we as readers are often better off if they would go through someplace like EReads who will do the "publisher part" of things like formatting and stuff. Smashwords and the like make it simple to upload a Word doc and publish your material, but it's seldom I've downloaded a books from there that didn't need work before I could comfortably read it. Smashwords makes it easy (so does Amazon DTP for that matter), but I wish all their authors would spend the time to get their books to look decent. Hope that doesn't sound to negative or anything, I think it's great all the avenues that e-publishing offers authors to put out their backlists themselves and if they have the know how to do it without help great, but some need help and seem to be forgoing it to do things on the cheap with mixed results.
Some of the Book View Cafe titles are authors bringing out their backlists. There are also CJ Cherryh and friends efforts at
http://www.closed-circle.net/ and the author consortium at
http://awriterswork.com/