A new browser extension has popped up, simply called Ponyhoof. It's primary function is to modify your Facebook theme with pony colors, as well as swap pony puns into various words. It's still in development right now, so I'm sure there are a few bugs, but if you run either Chrome or Firefox with Greasemonkey installed, it might be a fun one to try out!
Someone on Youtube who does various computer ponification tutorials created a video that includes it with a few other browser theme additions. Check that out at 2:21 in the video after the break if you need help!
Note: Some of these mods can cause issues with conflicting programs and older versions. If you run into them, bring them up at the actual Ponyhoof Facebook page. EQD is not responsible for any accidental breaking you manage to do to your browsers!