What I mean is, what unexpected but possible nominations for a film would be an indicator that it's going to be more popular with the Academy than we expected come voting time?

I'll show you what I Mean:

There Will Be Blood - Best Supporting Actor, Paul Dano
Sweeney Todd - Best Actress, Helena Bonham Carter
Juno - Best Director, Jason Reitman OR Best Supporting Actor/Actress
Atonement - Two Best Supporting Actress Noms, Ronan and Redgrave
American Gangster - Best Supporting Actress, Ruby Dee
No Country for Old Men - Best Actor, Josh Brolin OR Best Supporting Actor, Tommy Lee Jones [this would basically make the race for Best Picture over]
Michael Clayton - Best Director, Tony Gilroy

and my question after you've named these is: Which of these do you think will happen and will shake up the Oscars?

I think any acting nom for American Gangster would already show quite a bit of support for it.

I don't think Atonement needs 2 BSA noms to succeed, honestly. It's the kind of movie that can make a splash if it's in there basically. I mean, it has the BAFTAs and presumely the Globes to help it reach some momentum. I do think that a nom for either Keira Knightley or James McAvoy (or both!! - wishful thinking) would help, even if neither stands a chance of winning (the best shot is still Saoirse Ronan/Vanessa Redgrave?).