C# Coding Standard and Code Style Enforcer
IDesign (http://www.idesign.net/) have made available a coding standard for C# that they say has become a de-facto industry standard. I'll need to take their word for that but I've had a reasonable look and it's as good as any other standard to follow. You can download it here C# Coding Standard
IDesign have quite a good Download area with a quite a few sample projects that are worth looking at.
There is also a Visual Studio addin called Code Style Enforcer that checks and highlights any code that doesn't adhere to a coding standard. It's based on the stardard above but it is fully configurable so if you want to enforce your own coding standard then you can do that too. You can find out more information about Code Style Enforcer here.