Anyone who works with LaTeX knows how time-consuming it can be to find a symbol in symbols-a4.pdf that you just can't memorize. Detexify is an attempt to simplify this search.
Just draw the symbol you are looking for into the square area above and look what happens!
The symbol may not be trained enough
or it is not yet in the list of supported symbols.
In the first case you can do the training yourself.
In the second case just drop me a line (email@example.com)!
( I don't really find the time to actively maintain this version of Detexify but I am working
on a version that is much easier to maintain and has other benefits. )
You could spare some time training Detexify. You could also look at the source of the backend and frontend on Github (but better look at the new version). If you really, really like this you can also donate.or
Hosting of detexify costs some money. If Detexify helps you, you might want to help cover these costs. The backend where all the computation is done is running on a server that is sponsored by my employer Zweitag GmbH but the fontend is hosted separately and still needs to be payed for.
Detexify relies on HTML5 features so you need a fairly recent browser. Opera 9.6 / Firefox 3.5 / Safari 4 / Chrome should do the trick.
Philipp Kühl had the initial idea and Daniel Kirsch made it happen.