Neither of these is actually new, but they're new to me at least. In the last couple of days, I've stumbled on:

1) Ubuntu's Intrepid Ibex distribution release has a new utility/daemon called fancontrol- it works a lot like speedfan, but only works with PWM devices. It's in the package 'lm-sensors' and you set it up with 'pwmconfig'. Here's how to set it up. Documentation should be in /usr/share/doc/lm-sensors/doc/fancontrol.txt.

2) IBM's developerWorks has a new collection of scripts up to monitor and throttle power useage accordingly: [url=http://www.ibm.com/developerworks/opensource/library/os-smart-monitors/index.html?ca=drs-tp4508]Reduce your PC's power consumption through smart activity monitors
[/url]

Both of these require you to be somewhat familiar with the command line and basic administrative tasks.

Do you have any links? All I can find is related to NVidia graphics cards (or Win). (fancontrol in lm_sensors is old hat.)

Would any windows apps run under Wine? The new Gigabyte motherboards come with energy-saving software, but of course it's windows only...

Probably not, since I assume they require direct hardware access.