Electric & air here, too:
1. Most of the head & intake work I do is using a Makita grinder w/ a cheap dimmer switch to allow some RPM control.
2. I have a decades-old Mac Tools air grinder that I've done some head porting with, plus it was handier to use the air grinder when I was doing casting cleanup and throw profiling on my Eagle crank last year.
3. I have a couple of 1/8"-stem carbide burs that are good for doing certain detail work using a Dremel (either on the grinder or w/ the optional shaft extension).

Hello again; I forgot to mention that my air die grinders are "DOTCO'S" the best!!! There are a little pricey, but last a long time! I have an oiler set up on that air line for them. It help's lubercate them! I have had three grinder's since 1999, and never had them rebuilt!! Still going strong!!

Another from the bullet.