Not myself but have known a couple of people who have and they had some great experiences, one a middle aged woman who was planning to continue doing so on her return to Europe.
For her the prime goal was to do a week or two here and there amidst normal weeks of travellin about to ease the monetary strain, and then with the range of places available she also started looking at places in her book that were of particular interest and on top of that ended up getting some freebie tourist deals from connections with local operators that not only saved her heaps but also meant she could end up doing stuff she probably never would have intended to like swimming with seals.
If you peruse their noticeboard of new registrants you get just a sample of what is available and I've even seen some places that indicate a small wage and so I'd reckon there's every chance of supplementing funds even a bit more if you choose.
You'll always get the occasional dodgy operators for one reason or another, but they get taken care of eventually if enough people lodge complaints and you will also see on the web site of some places being suspended.
Another similar one you could look at is
www.helpx.net I think it is and tho not too familiar, I do know of one host in NZ from contact at the refugee place who seemed a ridgy didge type fella.
