What are some Android eBook options & eReader Apps (Kindle, Nook, Google Books, etc.)?
Aldiko:
Only does non-DRM'd ePubs.  There are thousands of these books available but you're not going to be getting newly released copyrighted books.  Great user interface but the no DRM limitation is a problem.  Aldiko also has a paid app that has more features but it still doesn't let you load new DRM'd books from the major retailers.