Now, scarves used to be a girl thing. However, as fashion has it for 2010, guys are now sporting them too. There many ways that one can wear it. Except if you are only doing t-shirt and jeans, try to go for something like this:
It's very simple and it definitely adds to the outfit. Try a plaid pattern or a dark colour that suits the shirt you are wearing. People will definitely notice. If you really want to go further, a funky hat and wrist accessories would do well too.