Actually this is great project to show how simple circuit and program can be in order to draw signals on VGA screen. For this only few components are needed like Attiny84 microcontroller running at 20MHz, few caps and resistors.
This small circuit is capable to update 800×600 VGA screen at 60Hz refresh rate. It takes Audio signals via ADC channel and displays on screen as a vertical waveform. There is also specially designed preamp that allows to connect an electret microphone to ADC channel so you could see your voice in screen.
Probably this is far from real scope, but it could be used as toy to play with your voice or other low freq signals.