I recently read a Q&A article in the latest Travel + Leisure (February 2011) about how a couple could transfer miles between their accounts and not incur fees. T+L suggested there was no way to avoid fees, but to look for the best bargains and cost-per-mile in FF program. I beg to differ.
For instance, British Airways' Executive Club program offers a Household Account option. This will allow you to add multiple people to a single household account where everyone can pool their miles. Then any one person from that household can use those miles, even if the trip is worth more miles than they've individually incurred. And with no additional "transfer/sharing" fee. In some cases, you can even add a friend to the household account so you can redeem miles for both of you, even if that friend never accrued miles on their own. Wunderbar!
What I also take issue with in T+L's response is their immediate suggestions to look at domestic FF programs. You need not be a resident of a country to enroll in their FF program, as long as you shop around for the best redemption deals and subsequent fees. Again, with BA's Executive Club program, they are part of the oneworld alliance. This means if you earn miles on any oneworld partner, you can later send in your used boarding pass from American and get credit on BA's account. A perfect example: I've been earning miles on BA for 5 years. I also have a separate AAdvantage account - both airlines are in the same alliance. I wanted to cash in all my BA miles for a friend and I to fly from Lima, Peru, to Easter Island, Chile. BA wanted 25,000 miles per ticket to redeem on partner LAN; American wanted 80,000 miles for the exact same route. So I cashed in 50,000 miles for 2 ticket by booking through BA and they placed us on LAN's flight to Easter Island.
Which means, it doesn't matter if I live in the US, I can still shop around for the best FF program that will allow me to cash in on the best cost-per-mile program even if it's on a foreign airline. In this case, I didn't need to cash in my American miles to fly on LAN, I could simply use my BA miles for the best offer. 50,000 miles is a lot better than spending 160,000 miles for the exact same route. You can start shopping by visiting the alliance home pages that will link you to the individual mileage programs. Check out oneworld, Star Alliance, and Skyteam for the best deals internationally - you may even be able to cash in miles from an international partner to redeem a domestic ticket.*
* Note about domestic redemption: Unless you never leave the US and never plan to, you should store your FF miles for status and international ticket redemption. Cashing in 25,000 miles for a Chicago to LA route would be a higher cost-per-mile redemption; whereas the Lima to Easter Island cost the same amount of miles, but I would have paid far higher for a full-price ticket. Keep your miles for when you absolutely need them, because airfare prices to fly within the Lower 48 will cost you more per mile than an actual full fare ticket.