My MacBook Pro runs hot -- too hot to use on my lap. My workaround is to put it on its Second Skin when its on my lap. Apple's official line is to call them "notebooks, not laptops" (i.e, you shouldn't use one on your lap), instead of addressing the issue. Yeah, right, how do you spell "cop out" again?.
Today I read on Digg that, unlike Apple, a German developer by the name of Hendrik Holtmann decided to do something about the heat issue and has written an application called smcFanControl that lets you set the minimum speed of your built-in fans.
I initially set my fans to maximum speed (6,000 rpm) and my MacBook went from too-hot-to-touch to cool in about a minute. One caveat, this beast is loud with both fans at 6,000 rpm. I've now got the fans at 3,000 rpm and you can barely hear them. It's a little warmer but nothing compared to how hot it would get previously. I can easily touch the vent by the base of the monitor and the first row of keys is actually cool now. I've got it on my lap at the moment, and I can actually rest it on my bare hands without burning them at all.
My only concern is that this application appears to keep the fans on all the time instead of firing them up when the temperature rises and it doesn't seem to return control to the built-in fan controller when it exits. It is open source, however, so someone can hopefully add these features in the future even if the original author doesn't have the time to.
Check out smcFanControl and cool down your MacBook/MacBook Pro!
The Men, rejoice: You can be fertile and use a Mac! article by Aral Balkan, unless otherwise expressly stated, is licensed under a Creative Commons Attribution-Noncommercial 2.0 UK: England License.

That’s pretty cool, it must be possible to access a temperature reading from the motherboard or cpu and then the user could set speed settings against the temp.
Ha. One of my laptops’ … er … notebooks’ manuals said how you should always use it on a firm, steady surface, and shut it down before moving it to another location.
Aren’t you concerned about some undocumented problems arising? I figure the fans are configured as they are for a reason…not that I know what those could be.
Hi Lee, I can’t see what could arise. Worst case scenario, the fans wear down faster and can be replaced. When compared to what excessive heat can do to the other components (including some of my bits), I think it’s a small price to pay! :)
Keith: “Manual” — I’m sure I’ve heard that word before somewhere… just can’t seem to place it! :P
hi, Aral
Sorry to trouble you. I am a Chinese Flex lover. I have found that the Quickstarts is very useful for the newbies. So I have translated some of these into Chinese and published them on my blog.(you can see it here:http://www.zhuoqun.net).However, I think perhaps I should get your and Adobe’s permission. I do not know how to contact you, so I cannot but leave a message here. If you don’t like me to translate, I will stop and delete all the quickStarts translations on my blog.
Best,
Dreamer
Hi Dreamer, I have no problems with this personally but it would be best to ask Adobe. I’ll bring it to their attention and perhaps they can reply here.
Thanks very much aral. I will wait for the reply.
A word of caution, after using smcFanControl on a Macbook Pro for a few days, Fan #2 is no longer registering any active speed. I’m guessing it’s either burnt out, or the program isn’t functioning correctly.
Here’s another option:
http://www.lobotomo.com/products/FanControl/