I’m reading a bit off-piste now as I get interested in  trying to define a virtual ethnographic field site. I like this:

I conceived of my field site as a network composed of fixed and moving points including spaces, people, and objects. [...] Another advantage of defining the field site as a network is that it is produced as a continuous space that does not presume proximity or even spatiality in a physical sense. Continuity does not imply homogeneity or unity; it implies connection. The continuity of a network is evident in the way that one point can (through one or more steps) connect to any other point.  (Burrell 2009: 189-190)

References

Burrell, J. (2009) The Field Site as a Network: A Strategy for Locating Ethnographic Research. Field Methods, 21(2): 181–199