welcome to Cruise-Chat.com.
Your subject line was truncated but I suppose you are looking for a Med cruise this upcoming December, right?
There aren't too many options at that time of the year. Costa Crociere would be the most obvious one. The company (a Carnival affiliate) operates several modern, large cruise ships in the Mediterranean during the winter months, as well.
If you go Costa's web site
you can choose your country and language at the top of the page. The site might not have December, 2005 departure dates posted, yet. If so, a cruise-specialized travel agent will gladly help.