Send files without pairing

Can anyone help with suggesting some software to help me do the
following?

I need a PC application that's capable of automatically polling for
Bluetooth devices, and then sending a file to any devices it finds. The
file would be a photo which users could elect to accept or decline.

I've experienced this kind of application previously, via a company
called Hypertag who used a system in a record store window that let any
Bluetooth enabled phone receive a free midi sound file if they remained
within a short distance of their in-store display.

Is there anything out there publicly that would let me set up something
similar?

Thanks,


Adam