Here's the Baseball Prospectus 2007 projections for center field (top 30), rated by VORP (value over replacement player)
Beltran, Carlos NYN 53.21
Jones, Andruw ATL 43.00
Sizemore, Grady CLE 40.87
Kemp, Matt LAN 37.19
Young, Chris ARI 33.15
Milledge, Lastings NYN 28.39
Baldelli, Rocco TBA 28.26
Damon, Johnny NYA 27.92
Cameron, Mike SDN 26.64
Wells, Vernon TOR 26.02
Pie, Felix CHN 25.27
Griffey Jr, Ken CIN 23.22
Granderson, Curtis DET 23.11
Denorfia, Chris CIN 22.88
Edmonds, Jim SLN 22.29
Crisp, Coco BOS 21.54
Hunter, Torii MIN 20.93
Winn, Randy SFN 20.53
Victorino, Shane PHI 20.27
Rasmus, Colby SLN 19.30
Blanco, Gregor ATL 18.12
Rowand, Aaron PHI 17.99
Richardson, AntoanSFN 17.27
Byrnes, Eric ARI 16.61
Church, Ryan WAS 16.38