Since there is an unbelievable amount, I'll try to boil the pics down to a few of the essentials throughout the years (only some of these guys aren't still crushes now, but most still are).
T(w)een Year Crushes:

Mark Paul Gosselaar -
Saved by the Bell, "Zack Morris"

Michael Manasseri -
Weird Science, "Wyatt"
I doubt I was the only fan of the show grateful for the episode where they finally stopped treating him like a nerd and had another character notice he was quite ripped.
Not Pictured (:D)
Other: JD Roth, Dean Cain, Oscar De La Hoya, Alfonso Ribeiro /
Wrestlers: Alex Wright, Dean Malenko, "Lord" Steven Regal, Glenn Gilbertti / "Disco Inferno", Bart Gunn, Jeff Jarrett, Chavo Guerrero Jr, Norman Smiley, David Flair,
Tony Williams, Bob Holly, Phil Lafon, Brandom Groom, "The Ringmaster" (Steve Austin, pre-goatee), Lodi, Rocky Maivia (Dwayne Johnson, pre-"The Rock"), Tom Brandi / "Salvatore Sincere"
Teen Years:

Austin St. John -
Mighty Morphin Power Rangers, "Jason"

Scott Bakula -
Quantum Leap, "Sam"
I actually took a bit of flack in the previous thread for this inclusion. Let me tell you right now: if you don't agree this guy is hot, you have no taste in men. I know his character on the show was insufferably clean and goody-goody and "gee, golly, gosh," but there's no short-changing that body.

Chris O'Donnell
Not Pictured Other: Tim Daly, David Yost, Jason Marsden, Davd Duchovny, David James Elliot, Henry Rollins, Jason Priestley, John Wesley Ship, Ben Stiller, Peter Scolari, Michael Madsen, Matthew Perry, Ewan McGregor, Eric Lutes, Chris Noth
Very Late Teens to Current Movies / Shows:

Byron Field -
Spyder Games, "Ivan"

Balthazar Getty - any and everything he does

Tim DeKay - the "other guy" on
White Collar
Not Pictured Other: Christopher Meloni, Matthew Settle, Jason Bateman, James Van Der Beek, Neil Flynn, Eli Roth, Stephen Colbert, Paul Gilmartin (TBS'
Dinner & a Movie), Colin Farrell, Travis Wester, Ioan Gruffudd, Shawn Christian, Mark Feuerstein, Nick Stabile, Will Snow, John C. McGinley, Keith Olbermann, Julian McMahon, Mark Valley