The LM386 is a low-voltage operation amplifier in an 8 pin dual in-line package. It can output .5 watts using 9 volts. Notable features are: suitable for battery operation, wide supply voltage 4v - 12v or 5c - 18v, voltage gains from 20 to 200, low distortion. The gain is internally set at 20, but with the addition of an external resistor and capacitor it can be adjusted from 20 - 200.
Links:
Datasheet | National Semiconductor
Cracker Box iPod Amplifier | A Blue Star
Mousey the Junkbot | Makezine
Tiny Amplifier | Electronics Lab
