I was reading slashdot today and found this article: http://blog.ksplice.com/2010/05/scalable-day-to-day-diskless-booting/
I remember having tried to do this in the past with an openfiler installation and an atom box, I ended up getting frustrated and moving on but this sheds a lot more light on how the process works and how to get it working. It’s kind of a dream of mine to be able to network boot a diagnostic distribution of Linux without having to worry about the HDD at all.