It would be great to have a time zone calculator as part of Gnome to simplify
those moments when you have to call someone in another timezone and want to know
what time it is there.

Alternatively, you may also want to be able to work out when a particular time
in another time zone will be in your time zone (so you know when to ring).

I don't imagine this would be too hard (and might be a good project for a
gnome-newbie) but it certainly would be useful.  It would be great if other
applications could hook into it too (see for example
http://bugzilla.ximian.com/show_bug.cgi?id=72431 ).

I know that this sort of thing can be found on the net, but the net is not
always avaiable and it never has the same yum UI that gnome has.