I have your answer at this site.
For Web document, no author (there is an example provided on the site):
Title Year, version number (if
applicable), description of document
(if applicable), name and place of the
sponsor of the source, viewed (Day
Month Year), URL (with either full location
details or just the main site details).
For Web document, with author:
Author (the person or organisation
responsible for the site) Year (that
the site was created or last revised),
name and place of the sponsor of the
source, viewed (Day Month Year), URL.
and an example:
The Body Shop Australia 2003, The Body
Shop Australia, Mulgrave, Victoria,
viewed 31 January 2003,