This software cocktail cooled my MacBook Pro by more than 40 degrees Fahrenheit:
- Install the MiniStat2 Dashboard widget. It shows CPU temperature as well as fan speed. This allows you to do easy before/after verification.
- Install SleepWatcher, which executes commands at wake/sleep events.
- Finally, install FanSpeed, which increases the minimum fan speed.
There are downsides (noticeable fan sound, uses more power), but having a laptop that I can have in my lap is well worth it.