A tutorial on making an LM386 audio amplifier circuit from Afrotechmods:
A tutorial on how to use the popular LM386 class AB audio amplifier IC to build a simple mono 1 watt audio amplifier. It costs less than $3 in parts! There is also a brief discussion of how to use high pass filters to prevent op-amp oscillation and subsequent noise.
More info at Afrotechmods tutorial page.
Check out the video after the break.