Jay,

I have just started back to the gym after way too long.
So here is what I have on my Ipod

Gaelic storm. Lots of good fast paced long sets.
I got the dvd and ripped them on to cds and my new Ipod.
they have a few slow songs but mainly very upbeat.
http://www.gaelicstorm.com/

Enter the Haggis
A little more rock than pop.
http://www.enterthehaggis.com/index.php

Another recommendation for ClananDrumma.
A friend of mine who is a marine said
"Listening to Clan an Drumma is very tribal.
It makes men want to fight and women
want to mate."

http://www.clannandrumma.com/