Ever looked at your task manager and wonder what all those and service that were running are? Or maybe someone sent you a file that you would like to check out before rung it? Now you can find out. What Is That File is a site that will suggest as you type (cool web 2.0 stuff) If the file isn't there and you know what it is, you can add it to their database.

Another place to help figure out what program a file extension may go with can be found here.