Free retreats & centers

Looking to get away from your crazy life? You don't need any money (tho donations are always helpful). 

Here are a few options (comment if you have others):
Pa-Auk meditation centers exist in various countries, including Sri Lanka, Singapore, Malaysia, Indonesia, Thailand, Nepal, China, Taiwan, and USA. I have not personally been but a friend of mine went for 3 months to the main monastery in Myanmar and highly recommends it.

There are also Goenka insight meditation retreats in more countries. The technique taught in the Goenka retreat is fairly scripted and a little bit limited, but many people have benefited from practicing it. 

There are of course many other centers around the world which you can find, but very often they are either not open to outsiders to come and stay, or they require extensive notice to be given, or they have high suggested donations for retreats, or they have some strange special ideas they may try to put on you. For example, I know a psychologist who spent 3 years in a Zen monastery in which all he did was polish a Buddha statue. That's Zen for ya. :) But, he felt it was helpful.