Why haven’t I found this any sooner??? WhatTheFont just uses your image and analyses it to find out what font is used to create the image. Too bad this isn’t automatically done by Photoshop. Now there’s an idea for a plugin! Have Font!
And another one that recognizes fonts, but this time you have to do the recognizing work, and the program leads you though a series of questions (interrogates you really) to find out what find it is you’re looking at. No upload required.