I routinely use singular they [1] when referring to someone where gender isn't relevant. E.g., "I want to find a new doctor; they should be smarter than the fool I'm using now."

What got me going on this was Douglas Hofstadter's "A Person Paper on the Purity of Language" [2], which I read long ago in college. For me it's been a very gradual change; I don't like language forcing me in directions I don't want. Similarly, I've experimented with E-Prime [3] over the years.

[1] http://en.wikipedia.org/wiki/Singular_they

[2] http://www.cs.virginia.edu/~evans/cs655/readings/purity.html

[3] http://en.wikipedia.org/wiki/E-Prime