Always a good thread to have where webmasters gather. Please list a favorite Firefox extension (or some other browser... I use Flock, which accepts Firefox extensions).

My current favorite...

This is the quickest, easiest, and most full featured screenshot utility I've seen. They tend to give you a free trial of the full "Pro" version frequently, but the free version is perfectly fine on its own.

Easy dropdown menu right on the browser bar allows option to take pic of either full page OR visible area only, lets you edit it, comment on it, add arrows shapes, highlights, text, crop it, email it, store it easily. It's a must for any dashboard.

Feel free to add your favorites.