Used Constantly Rated 5 out of 5 stars
Pros: Does exactly what it says: copies whatever you have selected (on a web page) while removing all formatting in the process. I use this extension constantly.
Cons: Needs an option to create a user-defined keyboard shortcut. Needs to be updated for FF3.0.
It does work with FF3.0b3 if you use the MR Tech Local Install extension to overwrite 'maxVersion' compatibility testing. You can also use the Nightly Tester Tools extension to overwrite 'maxVersion' compatibility testing.
Thank you Jeremy Gillick!