Well, with VaughanTown, it's possible. You just exchange your English conversation for room and board in Spain.
The idea is that a group of 'Anglos' - English speakers from all over the world, join a group of Spaniards who want to improve their English for a week of conversation in a super hotel. All you have to do is get to Madrid and back at your own expense and pay for any necessary accommodation outside of VaughanTown. They pay all the rest. Visit the VaughanTown website to find out more and apply.