While I don't have the desire to rant at length about DRM right now, I do feel compelled to make some mention of it on this "Day Against DRM". Others have explained very well the reasons to avoid DRM. This post, however, is a call to the big book-sellers to ditch the DRM.
Once upon a time, all songs in the iTunes store were clad in DRM. So I continued buying CDs. Eventually, Amazon started becoming a major player in digital music, providing DRM-free MP3's. While I would have preferred something other than MP3, I have purchased digital music from them. Around the time Amazon finally arranged deals with most of major labels, Apple started taking steps toward making the iTunes store DRM-free.
I recently purchased a NookColor eReader from Barnes & Noble. I am running a full version of Android on my NC, so I have access to the OverDrive app (for borrowing eBooks from the local library), the Nook app, the Borders eBooks app, and the Kindle app. However, I have yet to buy/borrow a single eBook from any of these. Make no mistake, I have bought eBooks, but only ones that are DRM-free. For now, it must be DRM-free or I will just look for a used dead-tree version.
Barnes&Noble, Amazon, and Borders: treat me like a responsible adult by offering the books I want DRM-free and I will buy them.
BTW, I have not yet bought any books from Christianbook.com, but I intend to. They have a good selection of books, both DRM-free and DRM-clad. You can refine your search to only show those that are DRM-free, which is what I do.