The Linux Counter Project
In response to the poll querying user's Linux Counter number, we feel the need to explain. Given that at this early stage 2/3 of the votes are "What's That?" we feel we should inform the general public of a way to Stand Up and Get Counted. Say it loud and say it proud - I Use Linux!
The Linux Counter is run by a nonprofit membership organization called the Linux Counter Project created on May 1, 1999, taking over the running of the counter from Harald Tveit Alvestrand, who has been running the project since 1993.
The Linux Counter is started as a "for fun" project to find out how many Linux users there are worldwide. The basic idea is for people to register themselves as being a Linux user. Of course, this way you won't get all Linux users counted as not every Linux user will register himself at the Linux Counter site.
So, the main purpose of the Linux Counter is to deal with statistics on all kinds of numbers related to Linux usage. It started with statistics on the number of Linux users and it extended to statistics on Linux users, the machines they use, software they use and in what part of the world Linux users are actually living.
A second purpose of the Linux Counter is to make it possible for Linux users to find each other. The Linux Counter is reporting Linux users sorted per almost any place in the world. So, when Linux users want their information to be public, you can quite simply find those users who live in places near you.
So, basically, it is an effort to number Linux users. They trim their numbers every year and de-activate accounts that have not seen activity for two years. I almost lost my place once or twice. If you've been counted, log in and check your information so as not to lose your number.
Most info here was leeched from: