[Analog] telephone call logging software and hardware. Originally developed as a product which I offered to my employer at the time 
(a telecommunications company), however they actually wanted a version which could log (and decode) digital audio streams, so this didn't quite fit the profile.
    
Features:

* Written for QT 4.1.4 (in c++) for code portability
* DTMF detection for logging of dialed telephone number
* FMOD library for audio (mp3 or wav recording)
* Automatically starts call logging when audio levels surpass a defined threshold
* One end plugs into a standard PC microphone port
* Other end goes between a normal telephone and the line

Hardware based on G.Forrest Cook's phone tap design: http://www.solorb.com/elect/phone/tap/index.html