Found exactly what I was looking for here.

The driver combines a several mount points into the single one

Actually I think this may actually be better then the Drive Extender things…

Ther’s also UnionFS and AuFS

Played with AuFS a little, and got it working on the laptop.
This is the mount command that worked:
#mount -t aufs -o dirs=/home/outsider:/tmp=ro none /mnt/aufs

Just need to get it working on the server now.