As a non-immersive RPer - i.e., I'm not in a totally RP corp because I also crave the action being in a nullsec alliance gives - my bio is not filled with IC information about Esna (you can look at his blog for that). Rather, I've made it my job to try and make people smile with quotes from friends, corpmates, and random passers-by.
I'd like to comment on something else I see sometimes in bios, though: ASCII art.
Sometimes it's offensive (I've seen plenty of ASCII art of people's genitals) and some of it is old (Brofist, skull and crossboes) but occasionally I see something amusing and impressive. Example - when I flew in Providence, there was always one U'K guy who had an ASCII U'K fist in his bio. A few weeks after that appeared, a CVA guy copied it... with a big X through the middle of the fist.