This will remove the shadow images deviantART adds under deviant thumbnails. Read the next paragraph:

I don't know if I'm the only person with this problem, yet wouldn't be surprised. You ever notice those little shadows that deviantART sticks behind deviation thumbnails? Yeah, well, I don't like 'em. They jack up transparent gif files. In your settings you can turn off the shadows site-wide. But, for poor little ole me, the shadows are stuck on no matter how many times I check/uncheck the box and hit OK. That is the reason why this script exists.