[iamwil]

I used .plan in college. Email was provided by a telnet system, and you can update your own .plan account and see what your friends wrote by fingering their unix account.

It's kinda like how statuses were used in AIM/ICQ, or if tweets/fb messages only held the latest message. A good modern example are how people use twitter profile bylines. Something pithy and clever to show how cool and funny you are to your friends.