jlmkey, past Princess passengers have the option to sign up for e-mail notification of any last minute deals. I posted this because there has been some discussion here about it: nobody ever actually gets any offers. This is the first really last-minute deal I've seen in several years.
But most of the cruise lines have really good deals from time to time. I would find a travel agency that specializes in cruises and tell them what you have in mind and they can be on the look out for you.