I've been using Skype a little bit lately. The main reason is that a programmer who works for me just moved to Venezuela, so we use it to video conference him into our weekly meetings, as well as for text chatting and occasional voice calls. Overall it works pretty well.
I have been using the campus Jabber server to chat with the consultants in our testing lab but hadn't really been using anything to chat with the programmers. Since we all installed Skype, we've been chatting through that, so I actually talk to them more than I had been, even though it only takes about 7 seconds to walk out my door into their office.
So I got an email from one of the campus security team saying that my computer was serving as a supernode for about 400,000 Skype clients. Basically, Skype uses a peer to peer network for handling traffic, and since I had a fast enough computer with a high speed internet connection that was always on and logged into Skype, I got volunteered to route calls through my machine for people. Yikes.
One site that talked about how to keep from getting wrestled into being a Skype supernode was much less technologically advanced than I hoped it would be. Their suggestion? Block Skype with your firewall and only run the program when you are planning to make or receive a call. That's not ideal, but I suppose it will work, except I now have to pick a different communication method to determine when we need to load up Skype so we can communicate. Google Talk may work, since you can make voice calls through it; it doesn't do video, but none of us are really that exciting to look at anyway.
So, the lesson for today is be careful with Skype.