I am not the author of the Headmap Manifesto. I am providing a mirror of this document because I think it’s amazing, and at the time I first started hosting it it was the only other place online to find it was The Way Back Machine.
Headmap Manifesto was written by Ben Russell and published in 1999. He seems to have disappeared from the web around 2005. Tish Shute, covering the Where 2.0 and WhereCamp events in 2009, wrote a bit about the history of the modern geolocative technology movement, including the Geowanking mailing list and Headmap:

The prime mover of the Headmap manifesto, Ben Russell, has retired from the scene – perhaps bored by seeing a radical vision gone thoroughly mainstream, or exhausted by the rigors of carrying an idea through the early blue sky years, or just s simply doing something else? I don’t know.

Headmap Manifesto (PDF)
Headmap Localis(z)ation (PDF), an expansion of the original manifesto. I think this was published in 2002.
The Headmap Redux (PDF). A further expansion of the original. I think this was published in 2004.
New: I’ve converted the Redux PDF into HTML, which you can download here, and I used the HTML version to create an ePub version that I’ve made available here. These don’t have any of the graphics, just the text, but I think they will be easier to read on modern tablets or e-readers.
There were also print versions of these books.
I wrote a little about the prescience of Headmap here.
Way Back Machine archive of headmap.org.