I don't really bite my nails, but I pick on the skin around them, so the sides of my fingers and the area around them looks really horrible, and more often than not, sore and even bloody. I do it when I'm stressed, mainly, and don't even realise it until it's very sore and hurts.
I tried keeping myself busy with something else, but pretty often I don't even know when I did it, I just pick something up, look at my hands and see what I've done....no idea when I did it. Maybe dipping them in Tabasco or something equally unpleasant would help, but somehow the idea of putting Tabasco on broken skin doesn't sound all that appealing to me....*lol*