Note: If you don't use or care about Twitter or browser extensions or the Web in general, you can safely skip the rest of this post.

One of the things that annoys me about Twitter is the constant "check-ins" from location apps like foursquare and Gowalla. Since I don't use these apps, I don't especially care that you're at the Starbucks in Dallas or that you're the mayor of your bus stop.

To solve this problem, I wrote a browser add-on called Twitter Filter. It adds a little "X" next to the source of each Twitter status update; if you click that X, you will never see updates from that source again (at least not on the Twitter website):

The sources you've blocked are listed in Twitter's right sidebar so that you can easily unblock them:

That's all there is to Twitter Filter, and it's a new type of browser add-on for me. It has options, but no options dialogs. There's no toolbar button, no browser sidebar - everything related to the add-on is controlled via the Twitter Web interface, so it's not so much an extension of the browser but rather an extension of Twitter itself. Go ahead and install it on a friend's computer and convince them that Twitter added the feature - it'll be fun! Be sure to come back and recount your grand prank in the comments below.