Here is something from D-Link support:
"How do I uplink to another hub / switch Print
You can always connect an ethernet hub/switch to another hub/switch. Some hubs/switches have uplink ports, and others do not. The configuration for all scenarios is listed below:
NORMAL PORT TO NORMAL PORT ---- CROSSOVER CABLE
UPLINK PORT TO UPLINK PORT ---- CROSSOVER CABLE
UPLINK PORT TO NORMAL PORT ---- STRAIGHT THROUGH/PATCH CABLE
NORMAL PORT TO UPLINK PORT ---- STRAIGHT THROUGH/PATCH CABLE
Remember, if you have a link light than the cable is right."
I've never tried it, but it seems easy enough to do. A router is also a hub. If ou connect 2 together you have to change the LAN IP address on the second router/hub. When connecting 2 routers together, connect the second one through a lan port, NOT the wan port.