The Desktop Webcam Widget
CamDesk is a free, open source, desktop webcam widget, that was created as home surveillance application. Although others have used it for demonstrations even with CamStudio, and QuickTime Player for screen casting.
WACC is a very well structured class written in Visual Basic .NET that allows to control Winamp from your VB.NET or C# application. It implements most of the functionality from the Winamp SDK. Controlling Winamp has never been so easy before.
emuSICK is a free multiplatform radio automation system based in the QT framework from Trolltech and the best wonderful FMOD sound engine. It allows to play multiple playlist grouped in blocks of time. You should use it in Linux, Windows and Mac.