Cross Platform (Mac and PC) Versions of Firefox and Thunderbird

Cross Platform Thunderbird

Cross Platform Firefox

In the read me file its important to note that due to a problem in the Mac OS X portable Thunderbird or Firefox script, you might need to launch START OS X Thunderbird or Firefox twice the very first time you download Portable Thunderbird or Firefox. I haven't tried this yet but it is due to a flaw in the script used to make user profile files compatible. The basic app is still John Haller's work which is distributed as a PC version at Portable Apps.