The mountable gadget I'd like to see

[Tom_imp]

well necessity is in the eye of the beholder I guess. The compass can tell what direction you are headed. this is the way I refer to navigate. I don't do GPS in motion, but I know if my destination is north west of origin, I am doing just fine if am heading more or less north or west. The thermometer, barometer, and altimeter can do a really nice job with short term weather prediction. Falling atmospheric pressure tells me it's about to rain while rising pressure tells me it is clearing up soon. I can also use the temperature for planning future rides. Wow 55 is cold; bundle up more next time I am going to ride when it is in the 50s. The altimeter just tells me how high I am. Actually it can help with riding in the mountains. Do I still have a ways to head up before getting to the other side of this range or not. Will I be approaching the river I plan to follow soon or is still pretty far down the range. I also like to fish and these instruments can often tell me what if any bugs might be hatching but that's for a different board.