New Project Brainstorming

I've been looking for another small Arduino side project to work on and one day I started looking at scopes and red dot sights. I'd really like to design my next project around a cheap scope or red dot sight, but I don't know what to design.

I've thought about making a simple electromagnetic coil gun, range finder, and sentry gun, but I was wondering if anyone can help me think up a different (preferably simple) Arduino project that incorporates a scope or red dot sight.

Any ideas?

ACOG knockoff
OR
Red dot

Did you ever do that exercise at school where you measure the height of a building by measuring the angle from the ground?

An inclinometer in the Arduino and one of those sights would be easy. I would pick the ADXL345 to measure the inclination. Lots of other sensors will work well.

MorganS:
Did you ever do that exercise at school where you measure the height of a building by measuring the angle from the ground?

Ahh...that's a good idea