Here’s some tracks with potential for remixes:

Jason Derulo – Watcha Say
Britney Spears – Womanizer
Deadmau5 – Ghosts N Stuff
I Remember – Deadmau5 & Kaskade
Ron Reeser & Dan Sanz ft Myah – Everything
Bassboosa – Wicked Game

I’m especially a fan of remixing remixes with originals, a la new verse with old refrain, or mix in an additional verse from the old version with the new background.

and here’s a couple other guilty pleasures I couldn’t resist:
Owl City – Fireflies
LMFAO – I’m In Miami Bitch
Mickey Avalon – My Dick