Gerber makes a safety knife with a serrated blade.

The Gerber has a rounded tip, so you cant jab or cut yourself with it if you are trying to get the knife between your body and whatever has you tangled.

Spyderco makes one too, the point isnt quite as round as the Gerber. http://shop.store.yahoo.com/landfallnav/ssk08.html

I couldnt find a picture of the Gerber.