I discovered the web service some months ago, when I needed to make a logo clearer and all I had was a lousy jpg. Working on the original image was a pain, so I decided to make it from scratch. Problem? Well, I asked what was the font used. The answer was a lapidary "Don't know what a font is!". WhatTheFont provided a fast solution and found the font.
The site is very easy to use. You can upload an image or link directly to the image source. The software will then ask you to confirm the recognition of every single letter found. And after that, it will provide possible solution based on the information gathered. Just try and see the result.