With the recent release of the Reactive Extensions for .NET (Rx) on DevLabs, you'll hear quite a bit about reactive programming, based on the IObservable and IObserver interfaces. A great amount of resources is available on Channel 9. In this series, I'll focus on the dual of the System.Reactive assembly, which is System.Interactive, providing a bunch of extensions to the LINQ Standard Query Operators for IEnumerable.

Some software, such as backup utilities, can use a large proportion of processor time and other resources. Often the user is given the option to only run such processes when the computer is not in use. This requires the detection of user inactivity.

MonoTouch allows developers to create C# and .NET based applications that run on Apple's iPhone and Apple's iPod Touch devices, while taking advantage of the iPhone APIs and reusing both code and libraries that have been built for .NET, as well as existing skills.

This two-part article is aimed at experienced C# .NET programmers who wish to write their own little computer languages (see part two here). Historically, this has been reasonably difficult due to requiring in-depth knowledge of compilation theory and/or the use of one or more tools, each of which had its own learning curves. Recently though, there has been somewhat of a revolution in this area, with tools being developed which greatly simplify the writing of compilers. The Irony Compiler Construction Toolkit for .NET is used in this tutorial due to the fact that it requires no configuration files etc. (Just drop the Irony DLL into your project) and it simplifies many aspects of compiler construction.

So you want to use a Ribbon toolbar similar to Microsoft Word in your applications, but you don’t want to purchase one from a third party. Well if you haven’t heard already, you can get a free one directly from Microsoft. Yes, you heard me correctly, FREE, and FROM MICROSOFT.

QuickGraph provides generic directed/undirected graph datastructures and algorithms for .Net 2.0 and up. QuickGraph comes with algorithms such as depth first seach, breath first search, A* search, shortest path, k-shortest path, maximum flow, minimum spanning tree, least common ancestors, etc... QuickGraph supports MSAGL, GLEE, and Graphviz to render the graphs, serialization to GraphML, etc...

The Task Parallel Library (TPL) is designed to make it much easier to write managed code that can automatically use multiple processors. Using the library, you can conveniently express potential parallelism in existing sequential code, where the exposed parallel tasks will be run concurrently on all available processors. Usually this results in significant speedups.

DotMSN is an open-source stand-alone class library to provide connectivity with the MSN Messenger service. The library is built in C# and can therefore be used by all languages the .NET environment supports. Because of a clean natural Object-Oriented approach the library is easy to use and implement. DotMSN is designed to be a flexible, robust and lightweight enhancement to any application. Applications of DotMSN vary from creating messaging robots to creating custom clients. If your application needs to communicate through the messenger service, DotMSN is your tool.

GLEED2D (Generic LEvel EDitor 2D) is a general purpose, non tile-based Level Editor for 2D games of any genre that allows arbitrary placement of textures and other primitive items in 2D space. Custom Properties can be added to the items in order to represent game-logic-specific data/events/associations between items etc. It saves its level data in pure XML files which can be used by any game development library/platform/language.
Check the video tutorials below to get an idea of its powerful features.
GLEED2D is free software and is written in C# and XNA Game Studio.