Are there any stand-alone C#/.NET Debuggers?
WinDBG with SOS extension
Following has series of 6 videos, to get started on WinDBG http://channel9.msdn.com/Series/-NET-Debugging-Stater-Kit-for-the-Production-Environment
WinDBG is also useful for following scenarios, where VS debugger is not effective/available
- Hangs
- Crashes
- Deadlocks
- Production environment
You should try mdbg.exe.
Also available in the Windows SDK directory on your machine, like C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\Bin\NETFX 4.0 Tools for VS2010.
It's not quite "standalone", but SharpDevelop might have what you're looking for: