No matter how accurately you type, you probably make loads of mistakes when using the PC. And the one mistake that I find especially annoying is when you misspell web URLs.
URL Fixer is a Firefox add-on that's been specifically designed to avoid this kind of mistakes. Once it's installed on Firefox it will check all the URL you enter in the address bar and correct them if necessary, thus preventing you from waiting for the page to load - before you spot the typo.
URL Fixer detects lots of possible mistakes, from entering .con instead of .com to misspelling the protocol (htp, htpp or even http:/ instead of the correct http://). What's more, URL Fixer is one of the first extensions to work with Fennec, the mobile version of Firefox.
The extension doesn't have any configuration options except for the option of confirming corrections, which you can enable or disable by right-clicking on the address bar.
Despite its apparent simplicity, URL Fixer is certainly a very useful extension that will help many clumsy writers out there.