Hiding System icons in Notification area?
Here is an excellent thread on XDA on how to do this the really hard way (manually, with de-compiling and recompiling the framework.) I would highly recommend not flashing the different mods from that thread because they are based on files from a different device. Also, backing up the files you will be playing with is a must.

I have not found any 3rd-party apps that can do this. Could be because this mod requires edits to system files that are very device-specific.