I'd like to write a simple program(preferably in C#) to which I sing a pitch using a mic and the program identifies to which musical note that pitch corresponds.

Thank you very much for your prompt responses. I clarify:

I'd like a (preferably .NET) library that would identify the notes I sing. I'd like that such a library:

1. Identifies a note when I sing(a note from the chromatic scale).
2. Tells me how much I'm off from the closest note.

I intend to use such a library to sing one note a time.