Bizak has an approximate Web 2.0 business valuation estimate called the Bizak Estimate. The Bizak Estimate is similar to many valuations in that it computes revenues times a multiple, however, from there we add a valuation for traffic.
So, if you’re spending more in marketing, advertising, SEO, etc. to receive traffic (more than you’re actually making in revenues) then this will subtract from your revenue valuation. Of course there are countless variables that go into a business valuation but the Bizak Estimate creates an apples to apples comparison that can be used as a starting point for comparative purposes and business valuations.