I do a lot of high powered video editing on my MacBook Pro and I often run compressions in the background while I'm doing other work. Sadly I've found that even when I'm using 150% of my cpu, the computer doesn't manage its fan to run at maximum speed, even when it's clearly and catastrophically overheating.
In comes this handy little utility from Hendrik Holtmann. Control your fan speed with preset preferences right from the menu bar or prefernces pane. Lovely little utility.
as I type this I'm running a heavy h.264 compression in quicktime and i've got SMC Fan control running my fans at maximum speed for a total savings of 10 degrees.
Please donate and support his free software.