MacDerm told me about the TinyUrl add-on for Firefox earlier today. It's really nice. You get a menu item added to the Tools menu in Firefox that is capable of creating a TinyURL from the site you are currently visiting. It also automatically copies the TinyURL to your clipboard for you. Sweet.
For those who don't know, TinyURL is a free service that can turn long, ugly URLs into short (tiny) URLs. Generally, you would paste the smaller URL into an email so that you don't have a long URL that wraps to the next line and becomes un-clickable - you know what I mean: everyone has had to copy and paste those long URLs piecemeal into their browser's URL bar!