I recently picked up a used Keeley Fuzz Head and I'm really enjoying it!

It's kind of a cross between a fuzz pedal and an overdrive pedal. Though it can get loud, it generates out a relatively low amount of distortion. Like a Fuzz Face (and my Fulltone '69 Pedal), it works well with the fuzz all the way up, using the guitar's volume control to control the amount of fuzz.

The sound is much more like an amp than most overdrive pedals. It's a fun pedal to "play".

I'm looking forward to trying it with the band on Wednesday.