One of the most useful sites I’ve discovered recently is called
What The Font?
If you’re wondering which typeface was used in a logo, a business card, a letterhead, you can upload an image of a few words and it will attempt to identify it for you. It works beautifully.
I was creating a DVD of a friend’s wedding and thought it would be fun to have the font in the DVD menus match that used on the order of service. So I scanned a line, uploaded it, and it turned out to be Mayflower. A quick search found a free version here. Wonderful! – it could have been a time-consuming job tracking that down.
If you don’t have an image, but you have a reasonable sample of the text, then Identifont might be able to help. Not as quick, or, in my experience, as accurate, but a good alternative none the less.