I made a patch to allow negative values in Degrees. You can find it at http://bebraw.googlepages.com/negadeg.txt. I tried to change the type to float but it seems it requires some change to DNA.
If I may make a suggestion...you should probably get rid of the clockwise button with your patch. If you set degrees to a negative value, and deselect the clockwise button, it spins in a positive direction again...it may be confusing to users to have both
paprmh: Thanks for comments! I did try to remove Clockwise button but it seems it is related to Screw tool. It basically sets the direction in which the screw is created.
That is a valid point though. Let's see if we can figure out a better solution for this.
Blender is growing very fast with lots of new tools, but i think that some of the "old" tools, with some care, can make wonderfull things. Thank you again!