While this is a very crude mod, my WRT160N was running a bit hotter than normal with the DD-WRT firmware (antenna output cranked up to 85mw). So, a simple mod with a 2" fan soldered to the power connector a 1.75" hole, and some temporary pedestals until I go to the hobby shop.
The temperature was getting up to 90 degrees and while the router has cooling ports on the top and is perferated on the bottom plate, it's not very efficient on the cooling side. With the fan mounted below (pulling air out of the base), I measured a 21 degree F cooler temp on the body of the router with the fan installed and operating.
Overall, definitely a plus when modifying these routers with better and more adjustrable firmware and (soon to come) external antenna's to handle the extra power output.