SeaMonkey 2.15
- SeaMonkey can be set as default client/browser on Mac and Linux now.
- The new IonMonkey compiler improves JavaScript performance.
- Preliminary support for WebRTC has been added.
- Image quality has been improved through a new HTML scaling algorithm.
- CSS3 Flexbox has been implemented.
- Support for new DOM property window.devicePixelRatio has been added.
- Support for @supports has been added (disabled for now).
- Startup time has been improved through smart handling of signed extension certificates.
- HTML5: Support for W3C touch events has been implemented, taking the place of MozTouch events
- Insecure content loading has been disabled on HTTPS pages (see bug 62178).
- Responsiveness for users on proxies has been improved.
- Fixed several stability issues.
This is a GREAT all-in-one client that I daily use on Ubuntu Linux 
Linux PPA:
https://launchpad.net/~joe-nationnet/+archive/ppa
Project Page:
http://www.seamonkey-project.org/
Brine Theme: (I'm creating and coming soon)
http://forums.mozillazine.org/viewtopic.php?f=3&p=12564665
