The top three, off the top of my head:
Kaley Cuoco
Kari Byron
Allyson Hannigan
Oh, and Tori Amos, let’s say circa 1999.
Kim Jong-Il
Winston Churchill
Gene Rayburn
Neko Case
Mary Louise Parker
Kristen Bell
Katherine Heigl and Elizabeth Banks
Mostly because I’m so annoyed at these two appearing in sex comedies Knocked Up and Zack and Miri Make a Porno - and resolutely refusing to appear topless. L-shaped sheets abound! Sex scenes featuring fully clothed people!
Heigl even has some cockamamie theory that appearing naked makes it impossible to get laughs. Bullshit. Julianne Moore did full frontal nudity in The Big Lebowski delivered hilarious lines at the same time.
If I could just see Josh Holloway nekkid, in my bed, I could die happy.
Also, Moore did lower frontal in Short Cuts proving she is a natural redhead.
Which they talk about in Knocked Up, ironically enough.
there is a nude of Daniel Craig, google daniel Craig nude bathtub
Not yet mentioned in this thread (unless I missed it):
Mila Kunis
Molly Sims
Aisha Tyler
Jenna Elfman
Salma Hayak
Rashida Jones
Taylor Swift
Mentioned, but worth a “Hell Yeah!!”:
Beyonce
Scarlett Johannsen
Yvonne Strahovski
Jessica Alba
Catherine Zeta Jones
Elisha Cuthbert
Seen naked (or at least topless) but I’ll take more, please and thank you:
Halle Berry
Marisa Tomei
Stacy Dash
Oh God, with you on that. Can Evangaline Lily come too?
My List:
Karl Urban
Jensen Ackles
Jared Padaleki
Jamie Lee Curtis (you know why)
Michael Clark Duncan (breaking out the tape measure for this one)
Cate Blanchette
Nostalgia Chick
Robert Downey Jr.
deforest kelley, in his youth (shut up, i have a crush, i don’t know why)
Amber Bensen
Hugh Laurie
Stephen Fry (standing next to Hugh Laurie, because I like it when they do everything together).
Bradley Cooper
Some of these names are probably spelled wrong.
ewww… remember for every every five ‘good body’ types (2 ends, 4 backs), you have 5 front linemen that you probably wouldn’t want to see naked.
Not a great ratio if you ask me. 
chicks on Glee
I forget which Thin Man it is, but Myrna has a see-through blouse on, and you can see there ain’t nothin underneath…
My votes (and I’ve already asked for forgiveness):
Maureen McCormick (When she was 21)
Ann-Margaret (before she turned 50)
Beyonce
Lucy Liu
Jennifer Love Hewitt
Virginia Mayo (when she did The Secret Life of Walter Mitty)
Liza Minelli (in Cabaret)
You could have them play flag football with no linemen. That fixes both that problem and the injury problem. And then you don’t have to take a snap under center, which could be really disgusting naked.
Where was Stacy Dash topless? LOL
There may be something to this, he was always waving that strange sexy microphone around.
As soon as I get to a computer unconnected to an IT department!
She appeared nude in the movies Illegal in Blue and Black Water. Beyond that, she posed fully nude for Playboy for her 40th birthday. To save Covered in Bees some time, here’s a non-nude picture of Dash.
Ya know, Brady Bunch fans always go on about Maureen McCormick, but I was more of a Susan Olsen (Cindy Brady) fan. Now don’t freak out on me here! She’s five years older than me, so by the time I was watching Brady Bunch in reruns, I was about the same age she was on the show, and I remember having a grade-school crush on her. “Marsha” and “Jan” were, to me at that age, more like babysitters than crush material.
Many years later I saw Susan doing a TV interview about that Brady Bunch movie that came out in the '90s (the one starring Shelley Long as Carol Brady). Susan had consulted on the movie, coaching the young actress who was playing Cindy, and I remember seeing her, now in her 30s, and thinking, “Hot damn she grew up nice!”
Anyway, I’m having a hard time finding a really good picture of her. Here’s one that looks fairly recent, posing with her son. (If there was ever a case of “he’s got his mother’s eyes” …):
http://beaniecat.blogspot.com/2009/10/susan-olsen-talks-to-ali-landry.html
Edit window: further research reveals I should have spelled “Marsha” as “Marcia”.