I can't for the life of me figure out which image skins the clock button in the systray. I would like to make it (The systray) smaller.....

***EDIT*** I guess it's not the clock button that prevents the startbar from getting smaller than ~32 pixels. It must be the systray. If i turn off the systray, i can size the startbar much smaller......Although turning off the systray seems to yield some odd button in the lower right corner when i have the startbar at the bottom of the screen.

Try looking at the taskxxx images in your theme. They change both the task bar images as well as the clock button.