setting up a cnc router is one of the more important chores I have found that needs to be easy but accurate. I bought one of these lasers and it really has become one of the most useful tools
http://www.lasercenteredgefinder.com/main.html
Since I zero on a jig or on material this makes it every easy to zero on a corner. but whats cool about it is setting up a cut or jig. you can use it to get something nice and straight. so all my jogs are easy to take off and put back on now. but it also lets you check a cut easier then air cutting since you can see where the cut will be.
I have never seen a laser with such a small dot. it is like a pencil dot.
Now I just need one in every size bit I use so I don't have to change collets (G)