Blutooth file transfer

Hi all,
I want to make a small device that can run bluetooth file transfer services, can pair with devices. It is supposed to be like a link between two bluetooth enabled devices. I want to use the usb bluetooth dongles available, a microcontroller with usb interface. Please guide me wether this thing is feasible or not. How do I start?
Thanx.

If you have two bluetooth devices why would you need this device or is for a store and forward system

I want to use this device as link between the two devices to increase the range of both.. so, any ideas??

Why not just build a passive repeater?

The bluetooth specs allow for a PAN (personal area network) so if another smart bluetooth device was used ... Presto!!! A PAN so the idea should be feasible. I don't know if I'd start with USB dongles, I'd rather start with a bluetooth module which is a lot easier to control. Basic AT commands over a serial line are used with modules as opposed to having the whole USB interfacing to deal with.