FPlot is a windows programm and a .NET library to plot and fit mathematical functions and data. The core concept of FPlot is that functions are entered as C# code and compiled on the fly. Thus the software is very fast and extensible.
Diablo 2 Slacker is a library written in C# for botNET that takes care of many of the details that you would normally have to handle yourself. It handles movement of the bot and includes services that the bot may require, like chicken and pickup.
OMRON FINS protocol ActiveX for Ethernet and RS232. Development under VB6.0, especially intended for Industrial Automation Applications. Started by the blogger of http://indanotes.blogspot.com
Extendable library for evaluating mathematical expressions.
Meyshan Wall, This is the ultimate wall paper changer, using Micro soft .Net framework, Meyshan wall would fetch public and private photos from Picasa, Flicker, Riya, and 23 Hq and from your local directory to display as wallpaper as per your settings.
A library of 3-D tools for vector algebra. Already in wide use for 3 decades in crystallographic applications.