Just a few of the ones I hear regularly that I can think of off the top of my head are:
Baby Bash - Suga Suga (2003)
Fabulous - Into You (2003)
Ciara - Goodies (2004)
Juvenille - Back Dat Thang Up (2000)
50 Cent - In Da Club (2003)
Eminem - Lose Yourself (2002)
Dem Franchize Boys - Lean Wit It (2006)
Nelly - Hot In Heere (2002)
Those songs aren't just played as occasional throwbacks, they are still in regular rotation. If I had to estimate, for my local Cumulus CHR, 15% of the songs are Pre-2008, 70% of the songs are from 2008-2012 and 15% of the songs are current. Cumulus has completely DESTROYED current radio in markets stuck with their CHR or Rhythmic CHR format.