There's a new closed loop router speed control on the market. www.superpid.com

It allows you to use your router as low as 5,000 rpm, with much more power at lower rpm's than any other speed controls.

I just got it wired up tonight, and hope to start testing it this weekend.
I made a quick video of the first run with it. Unfortunately, you can't read the LCD in the video.

I cut the case from 1-1/2" acrylic.

The router needs a new bottom bearing, so ignore the noise.

Oh yeah, it's a 15 year old PC 690, made in the USA. If anyone's interested, I can post pics of how I mounted the optical sensor on top of the motor, under the plastic cap.

http://www.youtube.com/watch?v=sIjUJm5CFVk