David Mackenzie's crime drama Young Adam is primarily Ewan McGregor's show, but Swinton is great as his lover (well, one of his lovers), who doesn't quite suspect his darker impulses.
If ever an actor seemed tailor made for a part, it's Swinton and Orlando, the gender-bending protagonist of this adaptation of the Virginia Woolf novel of the same name. Swinton is exquisite as both the male-born Orlando, and the female transformed Lady Orlando.
In The Deep End Swinton is an ordinary wife and mother until she finds herself covering up for a crime she believes her son committed and subsequently blackmailed for doing so. Swinton is fantastic as a woman pushed almost to the edge, who finds herself capable of more than she ever would have thought.
I've written before about my love for Swinton's performance in I Am Love, but I'll happily reiterate it: she is amazing in this movie. Seriously, just go watch it.
Julia, the violent, alcoholic protagonist of Julia, is easily one of the most unlikeable characters ever to grace the screen, but Swinton's performance is absolutely stunning, bringing shading and complexity to a character who is unquestionably a monster. Once again, I urge you, just go watch it.