Xfire

From Protocolinfo

Xfire is free (proprietary) tool for Windows that automatically keeps track of when and where gamers are playing computer games online and lets their friends join them easily.

[edit] Identification

[edit] Ports and servers

According to the Xfire official FAQ, Xfire always connects to cs.xfire.com TCP port 25999. It also connects to random UDP ports on game servers for getting game information, and random UDP ports on other client machines for doing typing notification, file transfer, and voicechat. The FAQ directs users to forward UDP port 25777 to their machines if they are behind a NAT, so presumably this port is more heavily used than others.