I'm designing a computer controlled toy, basically an arm that moves up and down. Only 90 degrees. I'm looking for some standardelectro-mechanical solution. I've looked up R/C servo motors. It certainly works. I've even got Servo + USB controller kit. However, (I'm not a mechanical engineer, mind you) it looks like an overkill for something that needs only two positions - 0 degrees and 90 degrees. Is there any widely used components (may be used in toys or robots) that provide this simple up/down kind of motion?