I am starting to build a few more pedals and I needed a small amp that I could keep on the desk just to test the functionality of the circuit as I complete it.  I used a schematic from runoffgroove.com called the ruby and installed everything in a metal Altoids can.

Its a 1/2 watt amp powered by 9 volts.  It has a volume and a gain knob that allows it to go from very clean to quite crunchy.  I plugged this into my single 12″ weber silver bell and was very surpised by the sound.  Its no tube amp, but the sound is very good…. and loud.  With an overdrive pedal in front of it, the guitar could easily be heard throughout the house.  With the gain turned up about 30% the amp goes into a light overdrive that is very touch sensitive.  Above that and great harmonics start punching through.  Here is a picture next to a standard size Boss pedal.