There are lots of online tools for shortening URLs, but one of the best is bit.ly. Not only does it shorten URLs, it keeps track of the URLs you have shortened and shows stats on them. Best of all, bit.ly lets you pick your own keyword to act as the short URL.
Unfortunately, the bookmarklet bit.ly provides does not take advantage of this keyword feature. I’ve cooked up this unofficial bookmarklet that will prompt you for a keyword before creating the short URL. Just make a link in your bookmarks with the following code and use it when you’re on a page you want to shorten!