If your case has two spots for rear fans, you can do the mod that Harper did for one of his rigs. He installed a Badong SuperCharger CPU Cooler.
Basically, it looks like a clothes dryer's vent hose, but of metal foil, that goes from a rear fan to the CPU. The rear fan is turn to be intake, and the hose bolts on over the heatsink/fan. It also has a 90 degree duct that mounts outside of your PSU to direct its exhaust up and away from the intake.
Here's a link to Badong's site, but it is in Korean. I use the Translate 0.6.0.8 extension in Firefox (definitely get it) to translate it.