A C program that continuously records an audio source (such as a microphone) and allows you to save off the recent data at the click of a button.
Leave it on and it will never run out of space because it will discard anything more than 30 minutes old. When something worth keeping happens, press save and the audio gets saved as mp3 to the hard drive.
Needs LAME in order to save off files (Download lame.exe and lame_enc.dll separately).
Updated to Version 3 with Stereo recorder, bugfixes and a new UI (Old version here).