http://accessories.musiciansfriend.com/product/Planet-Waves-SOS-Strobe-Pick-Tuner?sku=210066The link is to a small pick-sized guitar tuner that shines a strobed LED on the guitar string. You set what note you're tuning, then tune the string until the beams appear static.
This looks promising. The third string (D) on a guitar is 147hz. The Ducati service manual specifies 140hz (+/- 5hz) for both the horizontal and vertical belts for my '06 s2r1k.
I ordered one just now. Will let you know if it was worth the 15 bucks. (I posted this on TOB by accident.
Didn't mean to.)