Big Gator Tools tap and drill guide...

Freaking love this thing! Guide for taps and drills, has a V-notch on the bottom for tapping/drilling round and corners.

Never heard of them until on here recently, another great US company! Sorry about the crappy pic, but it's a pretty simple slug of finely machined steel!

It looks like a few metric and the rest standard . How about the longer one, whats it's range? But looks really useful.