Social networks are really something, they make life easier at times, but mostly you just dive right in and can't imagine your life without del.icio.us, facebook or myspace. Review is about the Social networks/utilities I use, reviews of them, and how can you benefit from them or just make your life easier.
Dividing them in categories, as usual.
News Hunting.
Bookmarking.
Group blogs.
Friends/Dating etc.
Photo/Video sharing.