I happened to be in college at the time, but many of my co-workers were people who waited tables on the side of their regular jobs. IIRC, one guy was a minister, another owned a catering business, and another was a teacher.
Another big plus if you're not married is that you meet tons of girls :)
I haven't been an employee myself, but I took a few cruises in 2007, and got to know some of the staff members. The pay is pretty basic, and the food apparently sucks, but there was no denying how much fun (and how much sex) they all seemed to be having, and seeing passports so full of stamps they had to order new pages every few months was pretty impressive as well. They hired computer-literate types for tech positions (the ships all have sat Internet) and newsletter-publication jobs - there are probably others for which I didn't speak to the employee.
If you were up for an adventure-type job, this might be something to explore.