On: Rails and Amazon: Libs and Plugs for EC2, S3, Simp...

[madmotive]

Not sure how RightAWS was missed from this post. It's well maintained by the guys at RightScale with support for EC2, S3, SQS, and SDB. I've found it to be the most well maintained for working with SDB. http://rightaws.rubyforge.org/

ActiveRecord2SDB is also worth checking out - it's built on top of RightAWS: http://activrecord2sdb.rubyforge.org