What's Your #?

It's been called pound (not to be confused with this pound) and hash. It looks a bit like a tic tac toe board. Take a closer look at the Shift+3 also known as the number sign.

Do you use # in front of numbers or do you prefer to let then stand alone or use № (numero sign) or some other prefix? Is it a matter of style or personal preference? In many fonts the # sign is rather boring. It often fails to capture the unique characteristics of certain fonts. It looks out of place. What's your take on the # sign?