Hmm... Quiet fans.
Earth the rad.
Mount a piece of metal grill/gause about 1.5cm from the rad, parallel to it.
Put a positive, or negative, charge of around 30 000 volts on the grill.
What happens is you have an electron flow from the grill to the rad. These electrons travel veeeery fast! They then drag the surrounding air with them creating enough flow to make certain experiments hover! (do a search for 'high voltage')
You should be able to use old monitors to get the voltage, but may need 2 or 3 to get enough amerage.
There you go: A dead quiet fan without any moving parts!
(It seems that if you have have a negative charge on the grill you may get an extra cooling effect in that the heat exited electrons are removed from the rad and replaced with calmer ones. Cant find the link to this info though any-more. :shrug: )