Originally Posted by
sdsearch
... maybe there are some people who find at least GPX useful?
I would be surprised. Many airline and hotel programs provide a limited facility to transfer points from one member's account to another for a fee, typically $0.01 each. This service is outsourced to Points International Ltd, the operator of the points.com site.
In my understanding, GPX is merely a tool for matching strangers who would like to perform reciprocal transfers. The transfer fees still apply and there is (or will be) an additional fee for using GPX, and the transactions count against the annual transfer limit. It's less expensive than buying miles or points, but otherwise

.
AA through Hilton HHonors and Diners Club at least
Note that AA has announced a restriction on the use of their outwards transfer facility, operated by Points International Ltd....
Effective April 10, 2008, non-elite status AAdvantage members must have a minimum available mileage balance of 25,000 miles in order to complete a transaction on the redeemAAmiles Web site. There is no minimum mileage balance requirement for AAdvantage Executive PlatinumŽ, AAdvantage PlatinumŽ and AAdvantage GoldŽ members.
I am aware of the converter on Webflyer.
The Webflyer tool shows the transfer path, but it does not actually execute any transactions.