It depends on my mood, I usually prefer to just listen to my favourite bands and songs which is mostly a mix of alternative rock & rock, indie etc.
But for workouts I also like to listen a lot of pop and just some upbeat random songs.
Destiny's Child - Survivor
Cheryl Cole - Parachute
Kat DeLuna - Whine Up
Britney Spears - Break the Ice, 3, Toxic Gimme More and others
Also Pink, Shakira, Nelly Furtado and other simple pop
More my own style:
Lots of Muse songs
Garbage - Run Baby Run - perfect for running motivation
PJ Harvey - Down By The Water, This Mess Were in and others
Also Audioslave, Stereophonics, Bebe, Kaiser Chiefs and lots and lots of others..
For cool down I prefer some random rumba beats or ambient/meditation songs or songs with nice vocals. I like Yasmin Levy, Gotan Project and others