New Zealand seems to be the most generous with this visa scheme, allowing citizens from over 40 countries to apply for a 1 year Working Holiday Visa (6 month limit per employer) and offers a chance to extend the visa by 3 months if working in the agriculture/horticulture/vineyard industry. US citizens, Canadians, Brits (2 year validity) and many, many more qualify; the Philippines was just added to the full list of qualifying countries. Those applying must be between the ages of 18-30 and the primary purpose for the trip is to travel (three months of study permitted). Since they are so generous with their WHV scheme, NZ citizens have over 30 countries to choose from for similar visas.
Australia has a similar scheme but citizens of only 19 countries are listed on their Working Holiday Visa scheme website. The USA is not listed there, but a one-year working holiday visa for US citizens, costing $549, is available through the BUNAC site which is a large student organization. I'm not sure if that's a special arrangement or if the Australian Immigration just has not updated their site. Aussie citizens can apply for WHV for 28 countries.
The most restrictive by far is the UK only offering their Working Holiday Visas to citizens of 6 countries:
- New Zealand
US citizens have 7 choices for Working Holiday Visas: Ireland, NZ, Australia and South Korea (1 year visa), with Canada and Singapore offering 6 month programs that can be read about here. There is also a 6-month UK internship program for US citizens listed on BUNAC's US page.
Many countries will issue work visas for certain jobs, such as Teaching English in Europe or Asia. Some people I met while travelling were taking up jobs without a visa, but I would recommend doing it legit to avoid hassles.
Working Holiday Visas differ from work visas in that the focus should be travel, but do allow for extended stays and ability to pick up jobs along the way. Overall, a great way to get out there and make it happen.