Some people might not know that it actually includes a feature specifically for this use case. If you start to type in a URL or page name similar to one already open in a tab, the awesomebar dropdown menu lets you jump to the already-opened tab.
And I'm not sure I really like it anyway - when I re-type a URL I'm usually looking to reload it to grab a fresh copy. I tab-complete the address of my development server and Hacker News very often; anything else I don't usually know the URL off the top of my head, I just remember that I have such and such doc on such and such desktop.
eg: % Firefox 7 memory