Sites like TinyURL.com were handy for a while, but any avid twitterer will tell you that every letter matters — and TinyURL addresses just have too many letters. Enter bit.ly, a URL-shortening service that creates much shorter URLs for more convenient link-sharing on Twitter and just about any other website. It does more than just shorten Web addresses, though. Bit.ly also lets you create custom URLs and track your links to see how many people have clicked on them. A Firefox plugin allows you to see where short URLs link to. A drag-and-drop browser button gives you one-click URL-shortening power. And a bit.ly browser sidebar gives you all of bit.ly’s features no matter where you are, without navigating to a new webpage. How many other services can offer all of those features? Short and sweet.