I think I'll go with microsoft surface, not a real tablet because its pc, not a phone, because its big. wtf is microsoft trying to accomplish?

I think microsoft should beat the shit of nokia and burn them alive. enough with the crap. getting angry for waiting a decent windows phone available on all countries.

you can use arduino with ultrasonic range detection (serial monitor), accurate as 2mm, I hope thats enough, but beware, maybe costs a bit higher than you think.