A lot of US companies put their HQ in Ireland because, they speak English (mostly), they have very low corporation tax and lots of golf courses - the Irish government also did an excellent job of marketing Irish-American links.

Unfortunately as soon as the EU cracked down on the corporation tax scams, eastern europe became cheaper and US companies cut back on golfing holidays they realized they didn't actually have an economy. But it was a great place to work for 10years - as long as you didn't buy a house!