So I was looking at Dominic West's (McNutty's) IMDB and saw a seperate listing from The Wire called The Wire: Chronicles. It touches on a few pre-series character lines.
I also read about Fellicia 'Snoop' Pearson, that she grew up on the street and was convicted of murder. She is a good character too, the scene with her shopping in the Hardware store is a good cultural juxtaposition. They also mention one of the side character's, a church Deacon I kind of remember, who apparently used to be on of the drug Kingpin's of Baltimore.

http://www.youtube.com/watch?v=wtvgw4xbRqo

Also, McNulty was in Star Wars Ep 1. Now I have to rewatch terrible movie to find him.