There was a time when bitcointalk had the option to display the animated signatures
I've never seen animated signatures.
Animated avatars were also disabled, except for the guys who had them before the new resolution was put in place. I think Yahoo, Ibminer, Vod and some other few members still have animated avatars
Those aren't annoying at all, and it's really too bad that's not possible anymore. The heavily animated advertising had to spoil it for the rest.