So yes, current favorite kickass chick is Kara "Starbuck" Thrace from BSG. I grew up wanting to be her. Although, I'm still really, really ticked off with her for the way she treated Apollo when he tried to welcome her back from Caprica. The girl needs to grow up and stop being such a bitch, although I do love her being a bitch, so what to do?
I also love Laura Roslin, and Boomer and Six. I've especially enjoyed the character evolution of the cylon girls. I've had a love/love relationship with Boomer from day one, and a hate/love relationship with Six, depending on the episode.
And yes, also Farscape's Aeryn Sun, Stargate: SG-1's Samantha Carter, and Stargate Atlantis's Teyla and Elizabeth Weir. In short, I love any portrayal of a woman that defies our still rather Victorian cultural norms. Women who are beautiful, smart, strong, and more than a match for any man they may run into. It seems a pity that they are so frequently confined to sci-fi and fantasy, although mainstream media may very slowly be catching up.
I also adore the girls of The Chronicles of Narnia. I haven't seen the movie yet, but have read the books many times, and Lucy is one of my favorite heroines of all time. I adore Polly and Jill and Susan as well (before she succumbs to '50's girliness).
I just started reading George R. R. Martin's A Storm of Ice and Fire series, and already have a few favorite kickass chicks in little Arya, and her mom, Lady Catelyn.
Ok, now I'm practically out of breath, and I've probably missed a bunch, but I'll come back, hopefully bearing a few new members!