In short, additional information which is displayed:
- PageRank (where we are going without it)
- Backlinks (from Google Yahoo)
- Page Views (very relative value ...)
- Alexa (Alexa Rank)
- Dmoz (is it present or not the page in Dmoz)
- Daily Ads Revenue (expected profit from advertising - again a very relative value)
- Net Worth (cost of the project based on the figures above)
As is obvious Net Worth figure is based on several specific and several relative values:)