I imagine that I should be able to pair my computer to my PS3 via bluetooth and use my computer as a controller for the menus and for typing. Are there any open source projects that have done this? If not, where should I start to write my own? Maybe just look at the drivers people have written to pair their computer to the PS3 controller?
I would use HIDClient on Linux for this. It makes your computer emulate a Bluetooth keyboard, and you can customise it at will (add scripting or triggers) since the source code is available.
I will let someone else research the equivalent software for Windows, because I could not find anything satisfying.