Found this interesting design on HardOCP.
http://babelfish.altavista.com/babelfish/urltrurl?lp=de_en&url=http%3A%2F%2Fwww.teccentral.de%2Fartikel%2Fartikel_173.html

Of interest is the use "ducting" plates attached to the underside of PSU. Looking at the numbers it runs hot, but I guess thats expected without a fan.

that heatsink design has been posted in these forums b4 , good idea but it'd be dependant on how much airflow from the PSU fan it'd be able to get, and it looks heavy enough to rip off your socket lugs, I don't think I'd like lugging my computer to a LAN with that on it

Well it may look heavy , but it only weighs about 90 g.
That is very lightweight.

And I asume that if you need more airflow than what your PSU can provide you can place a big slow turning (and low-noise) fan near it and improve it's performance.

Also at http://translate.google.com/translate_c ... l_173.html

And I agree , that the ducting plates seem to be a good idea. It
would be easy to create something similar yourself and use it with your current cooler .. it would likely increase the airflow around your cooler.
I cant say by how much without trying it first , but since something similar can be constructed from cardboard (which is practically free), it's definatly a thing to try out.[/b]