Do your north/south chipsets have individual heatsinks on them, or do they have the newer Asus heatpipe-across-your-motherboard coolers?
If they are individuals, they can be easily replaced by chipset coolers from a place like FrozenCPU.com. They have quite an assortment of cooling for 2 pin, 4 pin or hook-retained chipset coolers. Even if you have the heatpipe solutions, you could still remove the entire thing (I would rather find a small fan to blow across these, though) and attach separate chipset coolers. I know that the northbridge does typically get hot, so make sure your replacements are seated properly.