If you've got it, flaunt it. Willy Loman seems to be on to something in "Death of a Salesman;" being well liked and charismatic can directly affect your level of success in business and in life. A step by step guide to charisma from the BBC (via kottke.org) delves into why those with more captivating personalities always seem to wind up on top. Bill Clinton is actually known for being charismatic, and I can give you a first hand account (back from my days in school in Washington D.C.), that this guy could be talking to me about sausage making techniques and I would be captivated. I'm talking drool in the corner of my mouth, goofy-ass smile on my face, unconscious flirty head tilt/hair flip captivated.
The interesting twist is that the researchers say that it is possible to learn how to be charismatic...which I sort of buy. I know that, if need be, I can turn on the charm and switch into totally sweet/interesting/fun/animated mode...which is, admittedly, sometimes a nice break from my bitter/frustrated/snarky/know-it-all/despondent mode.