Dan Erlewine in his
Guitar Player Repair Guide (
http://www.amazon.com/Guitar-Player-Rep ... 0879309210) also recommends super glue for crack repair.
The crack must be cleaned, loose particles removed, and the crack closed as much as possible after the glue has been worked as deeply into the crack as possible. Because of the way super glue dries (most glues dry with either a rounded top, or a slightly concave top -- super glue dries with an irregular, jagged top), you have to gently raze the dried glue edge so it's flush with the surface, prior to sanding it with 0000 steel wool, applying lacquer, blending, polishing, etc.
I've done it on a couple guitars with very good results, though I wouldn't do it on anything super rare and valuable. I've been told this is how Taylor repairs cracks on guitars sent in under warranty, and the one cracked Taylor I've seen that they repaired looks very much like the two I've done.
Erlewine's book (which covers both acoustic and electric guitars) is a recommended investment, even if you don't plan to undertake any guitar repair yourself. It's a clearly written guide to the principles of guitar construction, what can go wrong, and what your options are when it comes to doing something about it.
It's like knowing a little bit about how cars work before you take yours to a mechanic. A little knowledge is a good thing.
Glenn//.