HelpX (Help Exchange) is "an online listing of host organic farms, non-organic farms, farmstays, homestays, ranches, lodges, B&Bs, backpackers hostels and even sailing boats who invite volunteer helpers to stay with them short-term in exchange for food and accommodation."

These are the HelpX experiences I've had:

Válor, Spain (Granada)

December 22, 2011 - January 7, 2012
HelpX in Válor: Celebrating Christmas

Dozza, Italy (Bologna)

March 2017