I'm not sure why I'm writing a web page on this, but since I've had some personal experience with gender-free pronouns (alternatives to "he/she" and the like), I guess I have the urge to share it :-).
The Gender-free pronoun FAQ is the nicest comprehensive source on the subject I've seen, including historical information (e.g. English used to have a word "ou" which only later developed into "he" and "she"; sporadic use of singular "they" goes back centuries), a long list of gender-free pronouns, and fairly extensive discussion.
Dmoz.org has a nice pronoun category with many links.
The gender-free pronoun "co" is in wide use in the intentional communities of the Federation of Egalitarian Communities. This occasionally happens in everyday communication, but more often in formal documents like bylaws and policies. The following examples are under "Systems and Structures" at the Federation web site:
This page is part of Jim Kingdon's personal pages.