Some countries (particularly the states) will start taxing your income once you start sending home sums exceeding the threshold (think it's $90k per year).
In the case of the US, the amount is $92,900 for 2011...but it is based on your income, not the amount you "send home". If you don't send any of it to the US, but make $142,900 for the year, technically $50k of it is taxable(at the 142.9k tax rate). Many non-US companies do not report to the IRS the amount you are paid as a US citizen...but if you lie about it, and get caught, you are subject to large fines and/or prison time.