Powersaving on thinkpads
Ted Tso has nice summary of how to save power on thinkpad x61. Few corrections/additions:

USB should be solved in recent kernels. You just need to enable CONFIG_USB_SUSPEND.

You can save additional 300mW by unloading sound driver (or enabling its powersaving), and ~1W by enabling powersaving in SATA; Kristen Accardi has patches for that. You can save additional ~500mW by spinning down the harddrives. (With ext2 it was easy, just set bdflush interval to half an hour; but I'm told it is harder these days. But maybe you can help with ext4? ;-). Lower screen resolution, lower refresh and lower color depth also helps. Difference between vga=1 and high-res graphics mode is ~500mW.

And then comes the crazy stuff. Try s2ram + resume, that saves 300mW, and I'm not sure why. One theory says difference is in PCI setup. Then... you are running CPU fan; probably unnecessarily. As much as 300mW can be saved here.

Good luck!

(Unfortunately, "extended battery" I have here is pretty much dead now, and it is not even that old:

present: yes

design capacity: 74880 mWh

last full capacity: 11830 mWh

battery technology: rechargeable)