Lola's Theme - speeds up and down to give you good interval training. And Chemical Brothers albums are great for the same reason. Although one of my friends runs marathons and swears by Eye of the Tiger for when she's flagging!
i tend to put my ipod to cascada album when on the treadmill(running) - it needs to be fast! On the other hand find this music too 'pumping' to listen to any other time. The current suga babes one is good too.
I do a lot of walking, a dull and repetitive activity if you are just burning off calories in all weathers. Currently I am listening to The Silent World of Nicholas Quinn (Colin Dexter), it gives you something to concentrate on.
As it happens I have just joined the gym. At my induction I jokingly asked if they could play more middle of the road - we are not all 20 years old. The (young) trainer said 'What about me - I have to listen to it all day!