DRBL - diskless remote boot in linux. I've used it quite a few times. It has clonezilla installed in it, which is the actual program I used for imaging computers. It additionally has the capability to image multiple computers at the same time over a network, and I believe it also has GParted and a few other utilities that would be useful. Also, there are good instructions on their and clonezilla's website.
http://drbl.sourceforge.net/
