Om Malik has posted some speculative valuations in extending his argument that unique users are worth $38 a piece based on recent acquisitions.
First of all, companies are generally bought for revenue potential. Someone produce the document that shows Weblogs, Inc. was bought for $25M on $1M in forecasted revenue. I seriously doubt it.
Myspace got a premium multiple because it is portal sized, growing and with serious revenue.
Blogs and blog networks right now should aspire to status as magazine businesses and find valuations in the single digit millions. Until they have real revenue, internet companies are highly valued at $1M per engineer if they fill a strategic or emerging niche.