Here in NZ most waitresses/maids also make minimum wage, and I don't think I've ever ever ever tipped housekeeping - sadly I also only tend to tip in good restaurants with excellent service (where I guess the servers make more money anyway) - rather than standard places - but thats just the norm here.
I personally (and not wishing to start a fight) think that tips should only be given for good service! I feel that the money I pay for food/wine should more than cover the costs of the restaurant including staff - if they don't make enough to pay their staff better thats not really my problem, I'd probably rather pay $2 more for food than be expected to tip all the time!
Anyway - thanks for the heads-up - don't want to make anyone mad at me while on holiday