Change Font Color of Taskbar Keys
Posted in the Home Screen thread but should be here too so it's easier to find.

Using a registry editor, navigate to HKCU/Software/Microsoft/Today/HTC Black.tsk (htc black.tsk being the active theme).
Edit the value of Color_CommandBarText to the be the color you want. If you do not know the code you can use the website in the link. The value starting with # is what should be entered as the value in the registry string. Replace the # with a 0 and add an additional 0 to the end (should end up with eight digits). If you do not see the string in your active theme, just add new string and select reg binary as the type.

The color of the softkeys when pressed also can be changed the exact same way but the string to be edited is HKCU/Software/Microsoft/Today/HTC Black.tsk (once again the active theme) with the string value being Color_CommandBarText_Highlight. This seems to only work when in applications that use the older style menu options at the bottom instead of the 6.5.x buttons.

http://www.2createawebsite.com/build/hex-colors.html