P&O Cruises - bring 2 friends for only $1 extra pp. (from $1400 for 4 people)
for a 7 night cruise, you will pay $699 for person 1, $699 for person 2 and $1 each for persons 3&4.
this means - $1400 for 4 people, so only $350 each for a 7 night cruise ($1800 for a 10 night) - these are fantastic prices!!
Worth checking it out if you are keen.
Might be more than 2 cruises, but the dates in my email are March and May 2011.
The cancellation fee is different for this cruise (guess because it's short notice anyway).