A cool little plug-in for Firefox which allows to use an external editor. This is A patched version of the original Editus Externus for

• FireFox 2.0: Attach:editus_externus-0.9.1-fx2.xpi
• FireFox 2.1: Attach:editus_externus-0.9.2-fx2.zip

If you use vim as external editor you should consider my Numbered Backups plug-in.

A promising new plug-in doing essentially the same is It's All Text! but it still is a bit buggy and won't work for me :-(.