Check this out (click for full-size):
While it looks like a font stupidly turned 90 degrees, it is not. It's a run-time mod to tweak texture coordinates.
To see the code, download
http://www.splatbang.com/files/gltrace.zip.
gltrace is a bit of open-source (GPL) code that provides an opengl32.dll replacement, wraps the original opengl calls, and gives you the opportunity to do other things. (I take no credit for gltrace, btw.)
Out of the box, gltrace saves many GL calls to a log file; in the particular zip I'm providing, I've commented out the logging calls (too many logs can suck up CPU), and instead slightly modified the wrapper for glTexCoord2f to tweak the texture coords (just to provide an example); hence, every character looks rotated. Yes, it's a stupid tweak, but the point is to make it available for more interesting or useful mods.
I had started playing with a mod that uses a double-height window to draw more than the 80x25 current restriction on the playing field. It could work... if you knew what to draw outside the default 80x25. That would require keeping track of what's been drawn so far, or finding a pointer to the map in memory... Unfortunately, I just don't have time to pursue mods like that, so I figured I'd make gltrace available/known to other devs.
After a build, you put the built opengl32.dll right into the same folder as the Dwarf Fortress exe and run. Remove the custom dll and DF will go back to using the system's. Feel free to send me questions you have to matthew.moss AT gmail.com, and I'll answer what I can.