Jonathan have sent us a link to amazing embedded project. Generating sound and VGA video signal on a single AVR chip is really challenging task. Everything is time critical here.
AVR Atmega88 microcontroller is clocked at 20MHz and so it generates 45 full VGA display lines at almost 60Hz frame rate. Sound is generated during VGA horizontal blanking periods. That gives a sampling rate of 31496kHz which is enough for good chip-sound quality. Sound player is capable to play four sound channels. And all that beauty is programmed in pure assembly language for best performance. Project files can be downloaded here.