It was mentioned once up above, but I've gotta recommend
DeployStudio. After using a stock NetInstall setup for a few years and getting tired of stuff breaking, I gave it a try -- a hurdle or two at the start, but then holy crap is it ever a million times better.
Waaayy more flexibility, no need to create actual NetBoot images based on entire masters (just a tiny boot-only image, then it grabs the rest off a sharepoint), and wwaaaaayyy faster. I was doing six simultaneous 16GB eMac images on a 100mbit network in about 15 minutes, which would have taken like a day and a half with NetInstall.