Thanks! Good guess, but no connection. My username actually stems from Darren Aronofsky's film; I had first seen it right after going through a particularly negative emotional "flare-up", so to speak, and I immediately identified with many elements of the film. Nina's mother acts very much like my own, plus I felt I could relate to Nina's naivete, perfectionism, egocentrism, and high level of self-criticism (the last two traits are MUCH more pronounced when I'm in the middle of a flare-up). After seeing the film together, my boyfriend and I developed our own lingo: when referring to a flare-up (past, impending, its characteristics, etc.), we call it my "black swan"; when referring to normal me, we call that my "white swan". So you could say that my username is a subtle reminder of which "swan" to always try to be.

...though now that I think about it a little more, one could argue that my flare-ups are black swan events for the people around me (if I understand the idea correctly).