Currently let's see...

*Katie Perry - California Gurls and Hot 'N Cold
*Flo Rida - Club Can't Handle Me
*kitty Cat Dolls...quite a few of them
*Kei$ha - Your Love is My Drug and Tik Tok

Mine changes often though, I get sick of some music so I switch out some of it. But that is right now! :)
Also as for the suggestion for Lady Gaga I would say Poker Face or Just Dance...they are her more popular songs, and will help you decide if you like her style or not. I don't. I can listen to some of hers, but she just really bugs me...lol.

my running sucks when i dont have great/fast songs.
love lots of those posted. may look into cadences.
love evanesence 'bring me to life' and eminem's newest song, not sure about the name, about getting over a drug addiction.
they both really say how i feel, about my new self, how i was dead inside before, but didnt know it. great for running or any fast cardio but you could do almost anything you like, i like up music even wt training.
i listen to npr alot. cant do cardio with it, but i can do weights or sit ups/planks. interviews get my mind off my muscles.

Anything with a good fast beat to it! It keeps me moving. Ive got a mixture of music on my Ipod.

Had to come back and add "3" by Britney Spears to my list...Something about it just really gets me moving!

Any techno when I'm running, it puts me into a zone:
lots of Prodigy, Chemical Brothers etc.

Usually a good mix of rap and indie. My latest playlist is a combination of Lil' Wayne, Hot Chip, Ghostface Killah, Ratatat, Gucci Mane, the New Pornographers, Amanda Blank, and the Hold Steady. I need stuff that either has really good lyrics to concentrate on or just an amazing beat that will keep me going.

My all-time go-to song for when I'm feeling wheezy is "Jump" by Van Halen, and the one song that makes me fantasize about being in an astronaut movie is "Starlight" by Childish Gambino (and my run fantasies are very useful. Mostly I imagine myself being chased by zombies through an Irish castle, or leading some kind of Roman war. It really keeps me going).

On my workout playlist I have:
Smash Mouth - All Star
Ke$ha - Blah Blah Blah and Tik ToK
JET - she's a genius
Jay Sean - Down
Enrique Iglesias - Escape
Nelly Furtado - Maneater
Miley Cyrus - Party in the USA and Can't be Tamed
Muse - Supermassive Black Hole
Village People - YMCA " I workout at the YMCA, so it gives me something to laugh about"
Green Day - 21 Guns
Weezer - Pork and Beans

I listen to the typical hip hop songs with a bit of odd songs mixed in.

Lately I am quite fond of 90s music

Chumbawumba: "Tubthumper" (No one recognizes this by the song title or group, but it goes: "I get knocked down/But I get up again/You're never gonna keep me down/I get knocked down/But I get up again ...")
Bobby Brown: "My Prerogative"
Peter Gabriel: "Big Time"
also his "Sledgehammer"
Heavy D and the Boyz: "Now That We've Found Love (What Are We Gonna Do With It)"
The KLF: "Three A.M. Eternal"
and their "Justified and Ancient" ("All gone to mu-mu land..."
Neneh Cherry: "Buffalo Stance"
Keith Sweat: "I Want Her"

And two really old ones, from the 60s & 70s, classic rock, good for lifting

The Cream: "Politician"
Led Zeppelin: "The Ocean"

Of new stuff, yeah, Kesha, Lady Gaga, The Killers' "Somebody Told Me," "Evacuate the Dancefloor" (by Cascada) and not quite so new, but still great, Flo Rida's "Low" and Akon & David Guetta's "Sexy B^&%$tch."

Funk and R and B, gotta have that strong bass to keep it moving LOL

saef, I love Chumbawumba! lol..

I love to listen to loud, fast music when I'm working out. Some songs currently on my ipod. Lately I've added some 80's that get me moving.

Black eyed Peas
Pear Jam (Ten album rocks)
C&C music factory
The Cranberries
Shakira
Carlos Santana
Gypsy Kings
Killers
Gwen Stefani
Nelly Furtado

To name a few.

Metal please! Power metal especially, great for cardio(but not weight training because you'll give yourself a hernia :D ). Power metal, symphonic metal, melodic death metal, folk metal, progressive metal... well, I think you get the point.