I've seen a few and that wasn't even online but in a meatspace, at a software conference. A few persons had bagdes with pronouns other than "he/she/they". Suppose that was a request of sorts. Although I haven't really talked to... err... such people ("them"? "xzem?" "xirzey'm?" what I'm supposed to use for "xe" and "ze" as a generalized group?), only saw that *ey (okay, does it work?) exist, so can't really tell more.