Working overseas is often seen as a way to cut costs, or in some minds the chance to replenish funds for further travel. Nowdays the chance to work overseas in a job which allows you to cover costs and save for future travel is becoming more rare. Visa regulations and work permits often make this a real problem. It is not impossible, but due consideration must be given to the legal requirements. Some trades and professions - Chef, Dive Instructor, Ships Engineer, Doctor, Nurse and others - allow 'bending' of local rules for short periods. Increasingly so, working in a foreign country is more a way to stop still for a while and 'just' cover local expenses.

CAMP AMERICA: A long established commercial entity. Quite a bit of work required with some free time.

Medecins Sans Frontieres - Doctors Without Borders: A well respected and worthwhile association to volunteer your skills. Not just Doctors, but nurses and logistical personnel are also required. Check their web site to see if you can help.

IWDA - International Womens Development Association. Supporting and empowering women in developing countries
Perhaps you have skills that you can offer to a project?

Live Work Play
An Australian based site, but with relevance for non-residents of Australia. An over all summary of 'Working on the Go'.