soundbrenner watch?

I suppose it depends on how much value you place on a metronome that vibrates on your wrist.

If you have a smartphone, you can install free tuner, metronome, and decibel meter apps. And, you can also install other useful music apps, like real time analyzer, recording, tabs, lyrics, etc.

I think this is more for drummers who need/want a tactile metronome experience.