BubbleIP

From the developer: "BubbleIP is a free program providing convenient way to connect computers on the Internet via static symbolic names even with dynamic IP. It uses email addresses to uniquely name computers on the Net, and only people from your "friends list" can connect to your machine via such name - it is the main difference between BubbleIP and traditional DNS services. You can use BubbleIP in virtually unlimited number of ways, for example, to play multiplayer games, host game server for your friends, remotely access computers, make PC-to-PC Internet phone calls - it can be used with any software requiring interconnection between PCs."

Requirements:

Windows (all) IE 5.5 or higher