AppAnalyze is a VB6 ActiveX component which recursively scans the desktop for all window handles, and brings up information on each one,
A little similar to WinSpy, only with programmatic control.

This gives access to your program access to textboxes, buttons and windows in other applications. It can allow monitoring of status changes within
other applications that don't expose a useful API, or any other form of access.

A VB.NET 2008 version is in progress, and I invite interested developers to come forward, and finish off this work, all in the essence of open source!

Full source code provided in the download.

Listed on Sourceforge!