I agree, although GIF is rather inefficient, and there are forums that forbid the posting of GIFs in favor of better formats like WEBM. I support the addition of WEBM support to LW.

Worked fine for me in Goodharr Ethology.

FYI I think gifs work just fine (you should be able to copy the image into the post). I'm not sure 

I'm hesitant to encourage people to use them willy-nilly, but they seem fine to use tastefully when appropriate.