If these, or the many, many other tweaks out there do not help, you can always try a custom ROM. I remember that the old Touch Pro 1 had really awful battery life with the stock ROM. Once I loaded a custom, I had a much, much better experience.
This seems to be the case with the EVO as well. Many of the new customs that are coming out are focusing on battery life. I recently fully rooted my EVO and installed a custom (
BuglessBeast v0.3) and have noticed an improvement with zero tweaks applied. I have the OC widget, but have not employed it thus far. It is still early on, but things are going well... =D>
Worth a shot if you are at your wits end on battery life.
FastRX8 did a great job on write-up and consolidation, rooting is pretty straightforward.
I expect that the Froyo release will contain a number of these fixes, but until then I am loving the custom scene.