Tonight is the premiere of Demetri Martin's new Comedy Central show Important Things. It comes on at 10:30pm, which gives you a half-hour of post-Lost brain-melting before you switch over to Martin's observational comedy. (On skydiving: "It's just showing off while you fall.")
Friday night is the premiere of Joss Whedon's Dollhouse. It comes on FOX at 9pm (following The Sarah Connor Chronicles at 8pm). Of course, you'll need to switch over to Sci-Fi the awesomest awesome that ever awesomed -- Battlestar Galactica -- at 10pm.. Friday nights are a sci-fi geek's wet dream, so if you plan on going out, make sure you set your TiVo.
And on Saturday night, Alec Baldwin will be back to host Saturday Night Live's Valentine's Day episode. Baldwin should make up for Steve Martin's surprisingly unfunny episode from two weeks back.