It's not exactly what you described, but close: http://www.mobilemouse.com/ http://www.mobilemouse.com/ I have the iPhone version, and it's pretty slick even

It's not exactly what you described, but close: http://www.mobilemouse.com/ http://www.mobilemouse.com/ I have the iPhone version, and it's pretty slick even with the wifi in between. That said, I'm still a bit miffed they didn't make it a universal app. :\