We actually share a housekeeper with my mom, my grandmother, and a couple of family friends. She does a mix of cleaning and child-care help for me and one friend; she just cleans for the others. She does half days for us two or three times a week (we trade around with my mom.)
I'm only working out of the home part-time, but I've had a lot of health issues that really limit me. (It's not so much that I can't do housework these days... I just hate doing housework.) Having her here gives me time to run errands without and active 2 yr old, actually get some work done, and take the occasional soaky bath.
This is the second housekeeper we have had, and she has been with us for two years and a bit. The previous one was actually with us for three years, but she did cleaning only and we really needed someone we trusted to help with our son.
We did not find her through a service; we found her through personal recommendations. (She used to work for my grandmother's neighbors until they moved.) We found our previous one the same way. So did many of our friends - asking people you know who have help is often a good way to find someone.
We trust her completely, my son loves her, and we couldn't do without her.
I am also one of those people who leaves cash and jewelry around, and we have never had any trouble. In fact, she sometimes leaves me a little stack of cash that she found when she was cleaning up!
As far as cost goes, she gets $280 a week from me and my mom for four half days, which she divides between my home and my mom's home. Those "half" days usually run between 3.5 and 5 hours, and she gets some flexibility around which days she works mornings/early afternoons and which she works afternoons/evenings.