Ebook Community on Yahoo! Groups (Click on “Join This Group!” at the upper-right.)
http://groups.yahoo.com/group/ebook-community/

MobileRead
http://www.mobileread.com/

EbookFriends.com
http://www.ebookfriends.com/archive/topic3_39.php

ebook88: ebook Resources and Forums
http://www.ebook88.com/forum.htm

Good eReader Forum
http://goodereader.com/forum/

Good Kindles.net
http://goodkindles.net