It is interesting, and surely not coincidental, that the two most talked-about websites of recent times—MySpace and Facebook—have the titles that they do. In their original definitions, the words "space" and "face" both refer to physical entities. A large part of the appeal of both websites is that they are virtual re-creations of physical objects: in MySpace's case, the high-school bulletin or message board; in Facebook's case, the college yearbook. So it is not surprising that the creators of these sites should have chosen names that reinforce the idea that they are somehow grounded in the physical world.
Yet what's notable about both "space" and "face" is that even before MySpace or Facebook came on the scene, both words had acquired meanings that went beyond the physical. The original, most basic meaning of "space" (ignoring "outer space" and "space-time continuum") is "unoccupied area." Somewhere along the line, spaces became value-laden: people (especially estate agents and theatre directors) started talking about them as being "interesting" or "full of energy." Then the word left the physical realm entirely: it became possible to apply it to relationships ("He didn't give me enough space") or discourse ("Andrea Dworkin opened up a space in which to explore male aggression"). From there, of course, it was only a hop to talk of spaces existing in that other non-physical realm—the internet. The word "face," too, has acquired various metaphorical and technological meanings: we now talk of "interfaces," of "face time" and of "facing ones's demons." It is because the meanings of these words have become so multilayered that they make such good titles, especially for websites that, while deploying cutting-edge technology, aim to promote that oldest and most basic of things—human contact.