[Tfug] Scheduling user group meetings -- tool recommendation?

[Chris Niswander]

Does anyone know of a decent open source / free system
for helping clubs / user groups to decide when
they should have their meetings to minimize
members' schedule conflicts?

It would be nice if various people could enter
their own scheduling need/preference data over
the Internet.

What I'm *not* looking for is a system that requires
everyone in the user group to run their entire lives in
the system through an exhausting adoption process.
I'd also kind of prefer not to have to enter everyone's
data for them.

I would be happy to end up with a result like
"Best Times (0 conflicts): 2nd and 4th Thursday of month 6:30pm-8:30pm,
3rd Wednesday of month 7pm-9:15 pm" 
to pick a regular recurring event date.

I have some design ideas but I'd rather see that
it's been done already. :-)

Chris