Depends who's calling. The default is a theme for an old show on TechTV called The Screen Savers. (Yeah, I'm a geek)
I remember that show! I loved it! (Clearly, I am a geek as well!)
My phone stays on silent just about all the time. When I am at work, it lives in one of my shift pockets-- so is fairly easy to answer.
When I work in Boston, I have dispatch's phone answer with the sound of an AED (LifePak 500)-- from "Do not touch patient, analyzing" to the annoying sound as charging to, "Continue CPR". If its important enough for them to call during work, its patient care related (they dont give us portables), and worth me answering....
When most of my partners from work in boston call its "Sailing up to Boston"-- Dropkick Murphys. One of my old partners gets "Bicycle Race", another gets "I get by with a little help from my friends" --Beatles... another "409" by the Beach Boys.