i have a small, battery-powered strobe light, and an acrylic-body guitar.

so what i want to do is wire up the strobe so that way whenever i play a note, the light flashes. does anyone know how i could do this?
You would have to probably get a piezo sensor and put it by the bridge. Then when the strings vibrate the light should turn on.
Epi Les Paul Standard
Vox AD50VT
AgresiveNapkins' idea might work, but I'm not sure how much power a piezo can put out. I know it's not much, though. Probably (I would assume definately) not enough to power a strobe light.

Something like this might have a chance of working with a few LEDs, though, maybe with some kind of amplification circuit between the piezo and LEDs?

Again, I'm not sure how much output the typical piezo has, so I'm not 100%sure if this'll work..
If you could build some kind of small noise gate into the guitar and power it off a 9v battery. On my noise gate the LED changes from green to red but I'm sure you could wire something similar to that system inside your guitar. If that makes sense.