Cast:
Dipre: Dwayne "The Rock" Johnsonn. (Obvious reasons)
Jacoby_Ellsbury: Matthew Lillard. (Annoyance factor)
a700hitter: Himself (Clint Eastwood)
bsox0407: Carrot Top. (Perfect case of gingervitis)
BSN07: Tony Curran. (Adam LaRoche was unavailable)
Example1: William Petersen. (Always pictured him as Gil Grissom)
Y228: Toby Maguire (Nicest guy i could think of)
Dutchy/Chamomille/ Imperial59/Bedpan Jack/ Yaz Sideburn: Collin Farrell (Filthy beard model)
yeszir: Jim Parsons. (Uncanny resemblance)
Coco's Disciples: Topher Grace (Hello Wisconsin?)
redsoxrules: Justin Bartha (Eh?).
Youk Of The Nation: William Shatner. (Played by his hero)
ORS: Jason Statham. (A badass playing a badass) Stone Cold Steve Austin, if he's unavailable.
VA Sox Fan: Felicity Huffmann (Like fine wine...)
Emmz: Isla Fisher (Tiny people are hard to find in Hollywood)
Jacksonianmarch: Andy Dick (obvious reasons) in his absence Danny Bonaduce (obvious reasons)
suns: Sean Penn (In complete I Am Sam character) in his absence, Justin Bieber
SOTK: Kevin James (The other King of Queens)
msubulldogs: Justin Chatwin (Tom Brady was unavailable)
TheKilo: Will Ferrel (Admit it, you two look alike)
SCM33: Michael Chiklis (The resemblance is growing as time passes)
italstallianion: James Gandolfini (Uncanny resemblance)
I shall continue to compile this list as i get more ideas.