It really depends on where you shop for your nostalgia....
If you are in a warm climate and want to go out and bust bad guy heads in a warm climate - whilst wearing a thin tie -then as has already been touched upon above, you will need the theme to Hawaii Five O. (Accept no imitations)
On the other hand if you are an old school Brit dripping money or a US kid from the wrong side of the tracks looking to right wrongs and bonk top fanny then you will need this tune.
http://www.youtube.com/watch?v=ykLCAfVa410
Apparently it is being redone as a movie. Please God be better than the Avengers movie.
It above is a John Barry theme and at the risk of being a bore can I sneak in a John Barry movie theme. Not necessarily his best but one that has a simple haunting power.
http://www.youtube.com/watch?v=ZGORPUzLxtU&feature=related