Today I contributed to a map. I did this yesterday as well. I even did this last week. In fact I've been doing this since the end of July 2009. As of right now I've done this 11,880 times. I'll probably end up contributing to this map again later on today and will almost definitely do it again tomorrow.

But this isn't your average user contributed or crowd sourced map. It's not one of the usual suspects; it's not OpenStreetMap, or Google MapMaker or Nokia MapCreator. It's none of these, but it's a map nonetheless and it looks like this.

Most of my contributions are in the centre of the map and towards the South West corner. I've also contributed to this map in other places and it looks like this.

Here most of my contributions are in the centre with a few towards the North West corner. Maybe the maps will make a little more sense if I turn on an underlying labelled layer.

This is the map of the last three months on Foursquare in London.

And this is the map of the last three months on Foursquare in Berlin.

Each dot is a check in and every time I've checked in, which is almost every day, I've contributed to this map. Now it's not a strictly geographic map in the normal sense of the word, but each check in is a geographically accurate (subject to the GPS lock that someone's smartphone has) affirmation that a place exists and that it's important to someone.

It's fascinating to see how the world looks when viewed by check ins alone, with the UK, Europe and North America's coastlines standing out like a night-time satellite image when there's no cloud cover.

It's definitely not your average user contributed map but it's a map I helped make in a small way and will continue to do so; though I know of one person who probably disagrees with me.