Let me take you to an online world that will be possible sooner than you think.
You come home one day and settle down at your computer for a little online socializing, Virtual Reality style. While you're still stuck interacting with cyberspace using a keyboard, mouse and plain old computer monitor, you've been drooling over the stereoscopic heads-up displays and 3D mice that are starting to come into your price range. Checking your list of bookmarks of favorite starting points, you decide to go to the virtual coffee shop. You could be instantly transported anywhere you like in cyberspace, but coffee shop regulars are known for their lively discussion and debate on a variety of subjects. After a mouse click and a couple moments of waiting for things to download, you appear at the entrance to the coffee shop.
Looking around, you see the shop consists of a small bar at one end, a large and improbable-looking collection of instruments being played by a many-armed robotic musician at the other end, and several chairs and tables in between. The walls are decorated with the artwork of several regulars, but you notice that several panels are not loading. Hmm... Her server must be down. You glance about the room for avatars you recognize. Now, the fact that someone looks a particular way does not actually mean he or she is the same person you talked to last week, but a quick cryptographic handshake and checking of public keys verifies that no one is trying to fool you today.
Hagbard (whose avatar depicts him wearing slacks, a tweed coat and a beret) is having a heated discussion with The Mad Jester (a gigantic, creepy laughing clown head) and Veronica (a robot of the 1950 cinema cardboard box sort) over the politics of government interference in cyberspace. They are pretty into it, and you decide not to get involved quite yet. So you walk over to the bar, you order a virtual cup of coffee from the bartender-agent. It's purely a symbolic gesture, but it adds to the coffee shop ambiance. You settle into a corner to watch the argument.
Spotting an acquaintance, you guide your avatar over next to him. Unfortunately, Chuck doesn't seem to be paying attention to his terminal right now --- he has a sign floating above his avatar's head that reads "lurking". Sighing (in real life), you look around the room a bit more, taking a minute to appreciate the pulsating fractal that adorns one of the walls. Noticing the background music has stopped, you click on the robotic musician. The playlist agent presents you with a list of songs it has, or the option of playing a song from your own computer. You decide to put on "Cascade" by the Future Sound of London, and everyone connected to the room's music stream begins to listen.
In the middle of the room Hagbard and The Mad Jester have given up on civilized discourse and started throwing furniture. In the process, a cup of coffee is knocked flying. The cup rolls across the floor by your feet, still full of coffee --- simulating coffee spilling all over the place would take too much processing time and bandwidth! The altercation only lasts for a moment, as The Mad Jester turns off his physics simulation and flies up to the ceiling. He hovers by one of the slowly spinning ceiling fans and begins to flood the chat channel with obnoxious laugher. Moments later he vanishes, delinked from the world. It seems he forgot Hagbard was the sysadmin for this room.
Conversation turns to other subjects, and you lose interest. You were considering going through your bookmarks and jumping to another world when you notice a cupboard placed against one wall that you had not seen before. On a hunch, you walk over and fling the doors open. Sure enough, your network usage spikes as the data for a new world is downloaded to you. Still standing in the coffee shop, you peer through the cupboard portal out into a forest. It is a beautiful bright day. Through the pine trees you see a castle on a green, grassy hill. What looks like a dragon lazily circles the castle, high up in the air. Feeling adventurous, you step through...