Kobo (if it's not there yet, should be any time now)
Remember - you don't have to have an ereader to download any of these. All retailers now provide a solution to read their books on your computer or mobile device.
If you have questions, please review the Q&A post below.
Enjoy! In the meantime, I'll be chewing down my fingernails as I wait for the first reviews to come in. Yikes.