Here's a cool widget. Symphonic
by Mindquirk Software is simple and to the point. Just type the name of the song you'd like to hear in iTunes and it begins to play. It won't kick you out of Dashboard to launch iTunes or locate your song. So when you're busy playing a video game widget or looking at your stock ticker, you won't lose what you're doing. It only does one trick, but does it well. I like it.