Now this is a cool sample - how to build a managed debugger. Some might say "So what?" but I think this is great way of getting a better understanding of the CLR and the workings of the debugging and profiling infrastructure of .NET.
Piccolo is a toolkit that supports the development of 2D structured graphics programs in general, and Zoomable User Interfaces (ZUIs) in particular. There are currently three versions: Piccolo.Java, Piccolo.NET and PocketPiccolo.NET (for the .NET Compact Framework). This makes it easy for Java and C# programmers, even those targeting PDAs, to build their own animated graphical applications with zooming, multiple cameras, layers, images, etc. Homepage
There are sample applications (mostly Java at the moment), and the download includes the source code of the library released under the BSD license.
This overview article at the SQL Server Developer Center provides a nice & quick rundown of new features for database development in Microsoft SQL Server 2005.
This month's issue of MSDN Magazine sports an article from Dino Esposito on the topic of script callbacks (read it). I consider script callbacks one of the cool features of ASP.NET 2.0, so be sure to check it out!