There are actually quite a lot. Those that were previously mentioned by Fancy, and more.

Rascall Flatts
Toby Keith
Trace Adkins
Sheryl Crow
Alan Jackson
Rodney Atkins
Steve Holy
Bucky Covington
Billy Currington
Brad Paisley
Sugarland
Gretchen Wilson
Keith Urban
Rhett Akins

There are more, but those ones are probably the more popular ones right now. And you also have some of the older or not as current country stars playing quite a bit like Johnny Cash, Jimmy Buffett and Lonestar.