I figured out how to do this a while ago, but I forgot to post about it. With the recent update to Crunchbang's theme, my changes got overwritten, and when I set them back again I figured I would post here in case anyone else was wondering about this.
By default, when using the Shiki-Statler or Shiki-Statler-Dark themes (or a lot of other Openbox themes in general), the bottom of a window has a rather thick window border on it. I'm not exactly sure of the reason why, but I assume it's probably to create an easy mouseover target for window resizing. However, it is more efficient (and easier) to use ALT-Right click to resize windows. If you hold ALT, right-click and hold, and drag the cursor, you will resize the window from whatever side is closest to the cursor when you initiate the drag. Much easier than having to target the window handles at all.
As a side effect, those pixels on the bottom of the window become wasted real estate, and since I have a pretty small monitor I find it worthwhile to reclaim them. I like to set my window borders to 1 pixel wide, so that I can still see where window edges are if they're the same color as my desktop, but you could also set the borders to 0 if you prefer.
To change this setting, edit the file /usr/share/themes/<theme name here>/openbox-3/themerc, and set the following:
border.Width: 1 window.handle.width: 0
In my particular case, here's the Emacs-fu I used to change the Shiki-Statler-Dark theme:
1. C-x C-f /sudo::/usr/share/themes/Shiki-Statler-Dark/openbox-3/themerc
2. C-s !!Global width settings
3. Set following variables:
a. border.Width: 1
b. window.handle.width: 0
4. C-x C-s
5. C-x C-c