Preferably free

... and easy to use, with a decent number of features? Hope that's not too much to ask, heh.

Trying to make some personal animated avatars/sigs for the forums I frequent

im also interested in this question
as i know, it could be done with photoshop, more advanced software is probably flesh (Flash Slide Show Maker is the program i used but its a trial version).
it would be nice to find a program that would not need any plugins.

If you are good at photoshop you can create animated gif easily using it. I use photoshop to create animated gifs.

I use Imageready in animated GIFs. But most of the softwares in the internet extract videos in an instant.