WinForms on Silverlight
The team has been obscenely busy shipping Silverlight v1.0 and working on Silverlight v1.1 so I haven't had much chance to post lately, but this stopped me in my tracks. Via Tim's blog I saw this implementation of Windows Forms on top of Silverlight by a company called Netika.
Having worked on the Windows Forms team for 5+ years I know how much work it was for our team to implement all these features on top of Win32 (especially ToolStrips). Seeing Netika implement much of the WinForms library on the Silverlight alpha in just a few months blows me away. They've implemented focus, text input including selectioin, combobox, ToolStrips with docking support, and my favorite, the design surface.
There's a whole set of demos here, click the image below to run the design surface demo. Notice they've implemented a preview as well, just click the green play button.