According to a recent report by Billboard, the highest-grossing Country artists in 2008 were Kenny Chesney, Rascal Flatts and Taylor Swift.  The 2008 earnings include album sales, online  music & merchandise sales, touring and ringtones.

Highest-Grossing Country Artists in 2008

Kenny Chesney = $90,823,990
Rascal Flatts = $63,522,160
Taylor Swift = $45,588,730