I agree completely with your caffeine recommendation.  I used to be mostly a coffee drinker, but then I would crash sometime late afternoon (and crash hard on a three day weekend where I wouldn't drink any coffee).  I've since switched to a green tea, and that seems to have mostly alleviated the crash.  I was simply getting too much caffeine too fast. 

As for music: I've lately found that Digitally Imported radio is awesome when my personal electronic/techno library gets stale or repetitive.  There's always something different there.