|With 100 million websites, and billions of clicks per day, accuracy for website statistics estimation and ranking services are understandably questionable. The top ranking services are:
1. Quantcast - despite a recent hiccup, it provides very accurate up-to-date account of traffic.
2. Alexa - the oldest service, but traditionally dependent on their add-in to collect statistics. Recently changed algorithm may improve their accuracy.
3. Compete - the slowest changing ranking, Compete consolidates ranking data from other sites.
Web site categorization is interesting, especially with the power of Web 2.0 sites in drawing large crowds and creating large user communities. These services, while not completely accurate to the last click, provide good estimates as to the popularity of web sites within these general categories.
* Top 100 sites - including the 2 superpowers Yahoo and Google, these 100 sites command tens of millions netizens. (I define netizens as unique visitors per month) I call these sites "Net Nations"
* Top 1,000 sites - these sites have 1 million or more netizens. I call these sites "Net Cities". These sites are well visited brands, like NYTimes.com or HP.com.
* Top 10,000 sites - these sites have 100,000 or more netizens. I call these sites "Net Towns". Many multinational companies have sites that qualify, like IBM.com or GM.com
* Top 100,000 sites (top 0.1%) - these sites have 10,000 or more netizens. I call these sites "Net organizations". Many multinational companies have sites that qualify, like EDS.com, Maryland.gov or Coca-Cola.com
* Top 1,000,000 sites (top 1%) - these sites have 1,000 or more netizens. I call these sites "Net groups", for clubs or families.
* Anything below 1,000,000 - 99% of the web sites out there have less than 1,000 netizens. These are fine for small businesses and personal publishing, but do not qualify as having a community of netizens in the Web 2.0 context.