In 1507 the German cartographer Martin Waldseemüller produced what is generally considered to be the first complete map of the world. His rudimentary chart proved an invaluable travelling companion for countless intrepid explorers. It remains to be seen if Randall Munroe's map of the internet will be quite so useful.

Proving that having time on your hands and an internet connection can be a dangerous thing, the university graduate from Massachusetts appears to have spent chunks of this year compiling a map that equates the relative size of social networking sites to fictional countries.

Far from being arbitrarily scattered across the globe, each website has been carefully assigned a seemingly mythical country whose land mass equates relatively to the site's popularity. As Mr Munroe (it is unclear if this is his real name or an internet pseudonym) explains: "This updated map uses size to represent to represent total social activity in a community – that is, how much talking playing, sharing or other socialising happens there. This meant some comparing of apples and oranges, but I did my best to be consistent."

Explaining the work that went into his project, completed last summer, he adds: "Estimates are based on the best numbers I could find, but involved a great deal of guesswork, statistical interference, random sampling, nonrandom sampling, a 20,000-cell spreadsheet...and gut instinct (ie making things up).

Mr Munroe is billed on his Wikipedia page as "an American webcomic author and former Nasa roboticist, as well as a programmer [who is] best known as the creator of the webcomic xkcd".

"Best known" may be something of a stretch for anyone not familiar with the outer reaches of the internet but xkcd has been his full-time job since leaving Nasa in 2006, and is a hit cult phenomenon that gains up to 70 million hits a month.

In a 2007 article in Wired, Munroe's webcomic (which is populated with drawings of lovesick stick figures) is billed as a resource that "revels in the human side of geekdom", and represents "a way for people who are unpracticed at talking about their emotions to articulate them".

Since it was founded in 2005, xkcd has garnered a loyal band of followers, many of whom have gathered in the real world to act out scenes from his comic strips. In one, an enigmatic dream girl leaves the comic's hero with a set of co-ordinates for a location, and a future time at which she wished to meet. The directions also led to a real place and a real time, and at 2.38pm on 23 September 2007, 1,000 of Munroe's fans from as far afield as Britain and Canada converged on a park in North Cambridge, Massachusetts. As the clock ticked over, Munroe appeared and addressed the crowd.

Munroe still draws his stick men, but his latest work is about the relationships between sites rather than people. Perhaps unsurprisingly given its ubiquity, Facebook occupies the largest landmass on his social networking map, and includes the "plains of awkward public family interactions". Twitter and YouTube are given honourable status, but spare a thought for MySpace.

The site was once the most popular social networking location on the internet and was bought by Rupert Murdoch's News Corporation in July 2005. Since then its popularity has waned and it now sits 30th on the Alexa internet traffic rank.

On Mr Munroe's Map of Online Communities it occupies a humble location next to LinkedIn.