There are a few threads on tipping housekeeping, and a few threads on not having the room cleaned every day. Some chains even gave bonus points for not having your room cleaned.

http://www.flyertalk.com/forum/hilto...s-per-day.html

that links to something similar on Starwood

The threads always fall into two sides.

Why tip somebody for doing their job

Tipping daily gets you better service

Personally I don't care if they make the bed or not, just give me dry towels and empty the garbage.