I really wanted to see what was inside those .xpi files that I install as plugins for Mozilla and I hacked the Blog This plugin from Phil Ringnalda to be compatible with WordPress. The installation can be a little confusing, but it sure is worth it for me. I might write a php packaging script for WP if I get bored (much like YABBOB). In the meantime, enjoy the Blog This for Mozilla hack.
PS: Rightful credit goes to Ted Mielczarek for the original code and idea. Thank you!