Jenna has been nagged by NAAG recently, to the point of obsession. It is also one of the molecules I included in the Synapse puzzle.
So, if you want to learn a little bit of nitty-gritty detailed neurochemistry of this exciting (as of recently) neuromodulator (and possibly neurotransmitter), you should check her two-part post reviewing what is known about it: Part I and Part II.