There are times I use Irfanview to display an animated gif on my desktop without any frame or borders. This is the kind of amazing I would use far more regularly if I had a white background (or was willing to change it).
I wonder which muscles need to be used to move a tail... Is it similar to clenching my butt? Hmm... This question's came into my mind after I read that one Calvin & Hobbes comic strip... It's better left unanswered. Animal tails are a cool mystery.