UTC (zulu) time display

[astar24]

Hello folks,
I would like to display a clock in one of the cell of my worksheet, and I would like it to be update pretty often. I don't really need anything other the 4 numbers (hh:mm) displayed in the cell as plain text, but i would like it to be updated every minute. I used the function NOW() but I have 2 problems:
-first: it doesn't recalculate if not every 4-5 minutes right now (this may be an easy question for you guys)
-second: I need the time to be UTC (military zulu time), and I can't go by adding the hours to the now function, because the worksheet needs to be used in different timezones, and needs to be independent. users cannot modify it.
maybe the best solution would be to link the cell to a web data source.. and have it update every minute. if you have any suggestion, please let me know
thanks in advance!
andrea