When should I call a job after an interview?

I applied to a nice Italian restaurant, and had an interview a week ago today. I felt the interview went pretty well, they did a questionnaire type thing, and I felt I answered most of the questions really well, and he agreed with me on a lot of the things I said. Although he did say he had like 15 more interviews that week, so it's a lot of competition. He said he would call me "sometime next week" (again this was last week that I had the interview). As I said it has been exactly one week since my interview and they haven't called. Should I call them today? Some people have told me it shows you really want the job if you call them. Or would that be pestering them? Should I finish out the rest of this week, and wait till Monday to call them? Or should I today? Also, if they don't call, and I call them, what should I say? Thanks.