Two Caribbean Cruises in the last two years, and NO stamps. Be aware: there are sometimes in the port offices "stamps", those are however Tourist stamps. You are NOT allowed to stamp your passport yourself with it! It can actually invalidate your passport.
In the last years stamps have become fewer and fewer... Singapore? its all electronic. UK? Nah... you are European, you are good.... sad. I liked to have those pages filled out with momentos of my trips. Heck, even the USA stopped stamping last year.