Right, I've just gone and found a handout I got last year. It says to do the online thing like this:
J, Smith. (2007)
Title,
http://www.webaddress.co.uk (Accessed on: 5th April 2007)
but saying that, looking online at other guides etc, there seems to be an awful lot of leeway considering that it's all 'Harvard'.
I've always referenced books in this manner:
In text: (Smith, 2007:
xi) or (Smith, 2007: 177) or (Smith
et al, 2007: 177) etc
In references:
Smith, J. (2007)
Title of Book, Publisher, Place Published.
where online I've seen guides suggest:
Smith, J. 2007.
Title of Book, Place Published, Publisher.
etc.
I guess it's just down to each department/school's preference. As long as you're accurately referencing though, they don't really have much to complain about.