You'll need to be more specific in your requirement.

Do you already heard of some Serial Port Sniffer software? That's what I would use, assuming I understand your requirement. http://www.hhdsoftware.com/serial-monitor

you could also build your own, just grab the Data, display it on a LCD,...or sending it on a USB port, and create your own software... does it really worth it knowing it cost 60$ ish for a decent really to go version?!? It's up to you to decide.