First there was Wwoofers (Willing Workers on Organic Farms) www.wwoof.org
Then came HelpX which members preferred http://www.helpx.net/
Now comes Workaway which folk tell me is the best! http://www.workaway.info/
With Workaway, from the hosts point of view, you will need to be able to provide volunteer work (around 5 hours a day), accommodation and food for your visitors. In exchange you can expect to receive around 5 hours volunteering per day 5 days a week. This can be anything which is within reach of a willing visitor. Some typical examples of exchanges have been; house painting, weeding, tree planting, baby sitting, doing the school run, cooking, shopping, general maintenance, fencing, office work, help with building, language tuition etc. Remember travellers come for a different experience to what they are used to in their own country. Many are students on a year out, but some are skilled professionals on a break and others come simply to practice a language. This means that they should be made to feel part of the family. Hosts should interact with visitors as much as they can. Workaway info is NOT set up to provide cheap labour. It is an exchange in which both parties should benefit.