Melbourne, Australia-based Flippa bills itself as the #1 marketplace for buying and selling websites. It is essentially an auction house, designed to bring together buyers and sellers, the kind of thing valuators love.
It appears to be working. In their own words, last year “Flippa buyers placed over 413,000 bids on auctions in 2012 and 29,022 websites and domains were sold since January… The total value of those sites and domains was over $22 million.”
Importantly, the “Just Sold” tab leads analysts to a listing of the last 2,000 transactions, complete with the URL, the sale price, the date established, visitor metrics, etc.