There is a date_offset setting the admin panel, under Setup -> Miscellaneous. Additionally, each user can set their own time offset in their profile, which is combined with the global date_offset. For example, if your server had a local time of 8:00 AM, and you wanted it to be 11:00 AM, you'd use a global date_offset of '3'. If a user wanted the same time to be 7:00 AM, they would set an offset in their profile of -4, so their final time would end up being: 8:00 + 3 hours - 4 hours.
Jason Rhinelander
Gossamer Threads jason@gossamer-threads.com