I've settled on:
u1: <greeting><urgency><question>
The reply is almost always: u2: <greeting>
u2: <response> u1: <greeting><urgency><question>
The reply is almost always: u2: <greeting>
u2: <response>For some reason that reminded me of this gem: http://www.bash.org/?23396
Not sure if I should be pleased or horrified with myself that it took me less than 15 seconds to find that link. :/
"Hi, what is the problem you're having?", the only answer to that is exactly what I want to hear. Not "Hey what can I do for you today" or anything like that to which the answer could start with a review, or an anecdote, or whatever.
So the other side of this is greet people with direction.