I’ve said before that I find the ESRI website confusing and hard to navigate. Splitting all the online help up by versions (e.g. 9.1,9.2., and 9.3) might be comprehensive. But when you’re just looking for a point to start, it causes headaches. Heck, even for 9.3, there are wholly redundant sections of text, hyperlinking you down one-way vicious circles.
Sometimes though you get lucky. So if you’re looking for the one place with good examples for getting started with C# in ArcGIS, go straight to this page in the ArcGIS Resource Center for .NET.