BooksonBoard now is showing a closed notice when you try to check out their catalog. They say they'll be back after "re-organizing", but if you have any books in your library there, I'd go make sure you have them all downloaded and backed up, just in case this turns into something more permanent.
I haven't heard any rumors yet on what will happen to the rewards dollars we have them (mine were only around $5, but that could have been a book purchase, if we'd had any notice ahead of time.
Book Reviews and Bargain reads for the Amazon Kindle, nook, Kobo, Sony and other ereaders, Kindle Fire, nookColor, Kobo Vox, and other tablets, along with some games, music, technology and computers tossed in now and then.
