Twitter
Of course, twitter has been around for quite a while. The popularity of the service is booming, because it is becoming more and more mainstream now. I myself joined somewhere in the end of 2007, when it was still underground… :p
Do you (actively) use twitter? And if so, what’s your account, do you use it on your desktop / laptop / mobile device … and which client(s) do you use?
My Twitter info: