Forums / IRC
The internet isn't just a place to search for information and browse various web sites. It is also a medium by which people across continents can communicate on any range of topics. It's possible to meet and get to know someone in other countries. I find that very interesting.
In the summer of 2002, I began to be active in a web forum where I posted up to 1,000 messages in just a short time. With a few clicks, a new message could be posted and read by many people. I became hooked, in a way. Web forums allow users to sign up, start threads, and post replies on the fly. These allow people to carry on conversations regardless of time or location. It is a great medium for discussing things and learning about people from different areas and backgrounds. I am currently a moderator of that community and active in various other communities.
Along with forums I began spending a great deal of time on IRC which is a real-time communications medium. The forums in which I were active also had an active IRC channel. This offered another way to communicate, get to know people, and otherwise pass the (read: waste) time. I continued "idling" in channels and eventually moved up to help operating a channel. I currently manage a server which is linked to the Chatspike IRC network.
Using the internet as a globally accesible communications medium can be quite rewarding. I've come to know interesting people from different parts of the world. It can be a way to help remote people, find others with similar interests, or find help oneself.