http://www.thermaltake.com/coolers/cl-p ... ess103.htm
Thermaltake's reputation isn't very good, but perhaps this is interesting. The idea seems to be using such a big heatsink that it will reach the airflow from the case fan.
New fanless CPU heatsink
Moderators: NeilBlanchard, Ralf Hutter, sthayashi, Lawrence Lee
Sorry. I didn't find anything in the quick search I did. A more through search gave this thead:
http://forums.silentpcreview.com/viewtopic.php?t=13410
http://forums.silentpcreview.com/viewtopic.php?t=13410