The Boss SD-1W is worth a look for sure. In the custom setting you get some added gain and a fatter low end. It's a really cool pedal. You could probably roll up to a guitar center and try one out.
Isn't the Ibanez BB9 supposed to do exactly what the OP is asking? I've seen it go for as low as $60 through MF but that sale just ended so it's back at $90.
