Cruise ship musician is a cool gig to get, a friend of mine did several 6-month stints as a drummer for a jazz quartet and loved it. He was suffering from cancer and he decided he was going to spend his last couple of years playing music he loved in an environment he always wanted to experience. Originally he had planned on one 6-month contract, but he got called back I think 3 times. He's since passed on, but he was never happier.
I believe he got his gigs through
Jobs, Online Resumes, Industry News - US Music Jobs - I believe they charge a monthly fee, I used to check them out when they were a free site.