A friend at ATI sent this to us yesterday. We asked them if they could stick it on their site, since we figured others might be interested.
It's a command-line utility for creating normal maps from high-res meshes, to apply onto low-res meshes.
It has a bunch of tweakable options, plus a handy realtime previewer. It also has maya and max exporters to the necessary NMF mesh format. Warning... the max exporter is for max v3 only at this point.
But it comes with full source code...
They welcome feedback at firstname.lastname@example.org.