[financegeek]

While the US will tax you as long as you are a citizen, you can take a credit for any foreign taxes that you already paid on the same income, which should prevent double taxing unless you happen to be in a very low tax country. If you had some kind of business setup to collect the income in the foreign country you could probably keep a lot of profits in the business and not claim much income for yourself, but it is something you'd probably want to talk about with an accountant and is probably different in the UK (I love UK tax forms by the way, so simple compared to ours!)

As for actual experience, I had a great time in Buenos Aires. You get 90 days visitor visa with a US passport and there is a good size population of ex-pats that take a weekend trip to Uruguay when they get close to 90 days, turn around and get another 90. A bunch of them make some cash teaching English and keep it all under the table, which I don't really recommend (I mean they still get you on VAT, but you don't want to mess with any laws in a foreign country if you can help it), but it isn't a bad place to be.