Why you keep calling it the Big Tower kemp? Typhoon man But ya, any of the ones that kemp suggested and I would like to add the Tuniq Tower 120 to the list. Friggin huge, but effective (we need to get a hold of a Ninja, Tuniq, and Noctua so we can have a big air guns matchup)
Well, that thing actually does have coolant in it, forget which one it was. That's cause it's made by Asetek, well-known phase-change company. So, they kinda made a mini phase unit. However, heatpipes for air I'm pretty sure are more effective (heck, the thing is in essence 1 huge heatpipe).
Yea they use a form of gel that expands into a liquid when it heats up and so pushes up into the radiator, gives up its heat cools and shrinks back down. Same concept as the Evo33 (very good budget cooler)
I've seen quite a few people at CeBit "type" shows using these HSF's on their display rigs. I have also heard that the performance is pretty lacking compared to some of the other more well-known setups on the market.