Things left for crew

Somewhere there was discussion of how people left things - clothing etc - for the room attendants on cruises.

I couldn't find it, so I wonder if people could recount their experiences? Just leave stuff in room? Ask butler or the room attendant if they or anyone might like x or y or z? What type of stuff left/given?

I'm anticipating being over baggage allowance coming home, so would like to shed a few kilos (in more ways than one!) after the cruise.