The Smokey Amp—an amp that fits in an old cigarette pack and is purported to be the best-selling guitar amp ever—is based on an LM386 circuit like the one you just built: http://www.smokeyamps.com/.

For other ideas on using the LM386 Low Voltage Audio Power Amplifier (including three other audio amplifier designs), take a look at the National Semiconductor data sheet for the chip: http://www.national.com/ds/LM/LM386.pdf.