We must say that we haven't thought much of the idea of multi-touch mice, but Microsoft's Applied Sciences team has managed to make a couple of prototypes that made the idea pretty enticing.
Multi-touch controls as you all know make interaction way more intuitive, and the capabilities are limitless. It's worth noting that the prototypes have different methods of retaining the classic mouse role and amplifying it quite a couple of times, to the point where keyboard is "for letters only".
First up is the almost-classic mouse with the "front hood" sensitive to touch which does a pretty good job. Next is the "armrest"-mouse which is more of a glorified projector which allows for two hand complex gestures.
We quite liked the stylish curved acrylic sheet mouse, codenamed FTIR (Frustrated Total Internal Reflection - I know I'd be frustrated if I had to say it every day sub.ed.), which had cameras on the bottom, as it was quite a looker as well. Last in line is the mouse with two plastic arms which enable independent thumb and index finger movement, and in between them these guys must've tackled every possible way to put this technology to use.
You can check out a demo video by CrunchGear here and a perhaps more detailed presentation here.