I've transferred UA miles to a program that actually allows you to use/give away/sell them, Southwest. Diners Club is running a great SW promo right now:
24,000 UA miles = 24,000 Diners Club points = 16 Rapid Rewards credits = 1 free ticket, good anytime on any flight with an open seat
I'll take that over a 25,000 mile award that is offered for one middle seat every day on a 6 am flight if you have status.