What to Watch on Sunday: Mad Men season ends, Sally Fields turns cougar

Mad Men (10pm, AMC) - In case you've been living in a spider hole, we're here to tell you that tonight is the season 3 finale of AMC's stunning series, "Mad Men." Last week's episode, despite the JFK assassination storyline, was a teeny bit of a snoozer. But perhaps that's only because the previous week's episode, in which Don was forced to come clean to Betty about his true identity, was one of the most powerful we've seen. One major development last week, apart from confirmation that Duck is completely devoid of a soul, was Betty telling Don that she no longer loves him (Also interesting? That part where she made out with her new boyfriend in the car). What happens tonight? Your guess is as good as ours, but our guess isn't as good as this guy's. Don't miss it!

Dexter (9pm, Showtime) - Quinn's very interested in Dexter's nocturnal habits, which doesn't bode well for Quinn's future. Meanwhile, John Lithgow's creepy Trinity killer is still on the loose.

Bored to Death (9:30pm, HBO) - In the first season finale of this great new show, the Edition magazine gang -- George (Ted Danson), Jonathan (Jason Schwartzman), and Ray (Zach Galifianakis) -- prepare for a triple-header boxing match against Richard (Oliver Platt) and his GQ crew. It's not pretty. It's very funny, but it's not pretty. 

Brothers & Sisters (10pm, ABC) - Not only are we still getting to look at Gilles Marini guest starring (forever, please!) as Sarah's steamy French love interest, tonight Nora (Sally Fields) turns all cougary and begins an affair with a younger oncologist working at Kitty's hospital, played by none other than Jon Tenney (you may know him as Fritz Howard on "The Closer"). And even better, Tenney's Dr. Simon will have a recurring role on the show (but only a 4-episode story arc). Gilles Marini and Jon Tenney (not to mention Rob Lowe). Sigh.