Pretty much just the other's people have mentioned. Maybe it would be alright to include a one or two line signature now to help differentiate everyone and to promote their work.
I don't like that idea. Part of what makes Hacker News great is the forced absence of comment self-promotion/signatures and a extremely high focus on what's being said rather than who says it.
Anecdotally, if I find myself particularly interested in what someone says I'll visit their profile to learn more about them.
