GIF blocker for Chrome.
Another GIF blocker for Chrome.
GIF blocker for Firefox.
Another GIF blocker for Firefox.
Here's a short guide for disabling animated images in Chrome, Firefox, Internet Explorer, and Opera.
There are also a handful of text-based web browsers.
And if none of these work for you, just do a quick google search around. There are plenty of solutions you can use for yourself so you don't have to be bothered by headache-inducing sigs (like mine), without imposing on anyone who likes to use gifs.