You can't bypass Paypal's servers, if thats what you mean... if you are looking to have some kind of site where people can trade money quickly - I would use the conventional way of withdrawing money from paypal (the user sends the money to your paypal account), at which point the money goes into his website "account"... at which point your users could shift the "virtual" funds around between each other quickly, and perhaps have a "withdrawal" button that would submit a request to you, who would then actually transfer money to them via paypal again.
