I find getting tax refunds to be far too difficult abroad. In Argentina last year, I bought about $3000 of goods and exported them with me. The agents at the airport were only able to process the tax refunds on a small fraction of my overall purchases. I did follow the "rules," but the exceptions to the rules and the bureaucracy were vast.

Canada, IMHO, has the best system. The European countries and others would benefit in sales if they improved the ease whereby foreign nationals can receive refunds on all exported purchases. If the US had a national sales tax, I am sure we could learn a thing or two from the Canadian system, as well.