if you want to mention a member (presumably to notify them via email they're being talked about) post it by preceding their user name with an 'at' symbol...
as in [member=3]drewactual[/member]
when you use it, you'll notice the username list pops up and drills down as you start typing the name- which is clever so you don't have to remember how it's spelled or waste time typing it out- but maybe bad if users have similar names and you choose the wrong one.
this will dispatch an email to the user giving them a heads up their name is being used in vane.... or they have an admirer... or 'sumpthin like that.