Number of google hits searching for:

bill gibbons: 1,850,000
ron ramsey: 747,000
zach wamp: 128,000
bill haslam: 71,700

Gibbons has an advantage of sharing the name of famous ZZ Top guitar player Billy Gibbons, and Ron Ramsey's name is pretty common. So with some refinement:

continued...

ron ramsey governor tennessee: 23,100
zach wamp governor tennessee: 20,500
bill gibbons governor tennessee: 14,100
bill haslam governor tennessee: 6,400

(Ramsey may still have an advantage because he is Lt. Governor.)

Campaign page ranking:

gibbons2010.com: 4/10
zachwamp.com: 4/10
billhaslam.com: 3/10
teamronramsey.com: 3/10

ALSO:

Google news search:

ron ramsey tennessee: 17,542
zach wamp tennessee: 7,569
bill haslam tennessee: 5,322
bill gibbons tennessee: 71

Google blog search:

ron ramsey governor tennessee: 6,083
zach wamp governor tennessee: 4,194
bill gibbons governor tennessee: 3,742
bill haslam governor tennessee: 2,157