Spicebird

Spicebird is a souped up collaborative client (i.e. email client with extra stuff in it) that integrates with RSS Feeds and IM (GTalk./Jabber). It feels a lot like Thunderbird.

It is currently at 0.4 Beta but is working well. I escpecially like the RSS Feed and Clock integration. I tried installing the Enigmail Add-On but it would not support it.

Nevertheless it is a pretty cool tool. Just download it here , unarchive it and ./spicebird and you are good to go.