Does it ever happen to you that you don't remember the Latex code for some mathematical symbol? What can you do then except wading through pages of Latex symbols trying to locate the right one? Well, no more! Detexify is a great new service that allows you to "draw" the symbol you're looking for:

... and it will suggest the Latex code.

Detexify is a learning OCR classifier, and can be "trained" by users to improve it's performance. Kudos to the creator of Detexify for a great project. It will definitely be useful...