A wireless bridge using Dlink DWL-2100APs
This doesn't seem to be well documented - I had to do this at home to connect two parts of my home network together.
A bridge connects two parts of the same network together. The ends of the bridge are symmetric, and configured similarly.
You need two Dlink DWL-2100 APs. Put them both into WDS mode (in the wireless config). Put the mac address of the other one in each (obviously, this scales to multiple APs). Set up the same encryption key on each. Plug each one into the cabled ethernet in that part of the network, and restart. You then have one large network made up of the two previous fragments.