I\'m writing a Facebook canvas webapp that performs a login (using urllib) to a third party website and performs actions on behalf of the user. This means I have 2 accounts; the
I guess you could store the logins ONLY on the client, in some sort of local storage and do all the actions related to the third party, from the client in JS.
This of course would need some change in the architecture of your app if you tought to do all this from your server, but that would possible for sure, you can event make client JS send data to your server after it worked so you can log data from the interactions with the 3rd party.
Furthermore it has the advantage of distributing the load on the clients
I know you didn't tag the question with javascript and you seem to want a server pure solution, but It seems the best solution to me. the user keeps its data ..