Top 10 U.S. Sites, July 2009; source: comScore

Top 10 U.S. Sites, July 2008; source: comScore

Our Analysis

Facebook is the only new entrant to the top 10 since one year ago, moving CBS out of that esteemed company.

It's a little surprising to see that Yahoo is still very competitive with Google, showing that Yahoo's portal approach is still paying off, even in this late stage of 'web 2.0.'

A scan of the top 50 reveals some other big moves over the past year:

• Twitter has entered the top 50, in at number 42 with an estimated 21.2 Million monthly uniques. Twitter first entered comScore's Top 50 in June '09. Note that comScore probably undercounts Twitter's audience by a lot, because many Twitter users don't visit twitter.com but use third party clients. We reported last week that an estimated 65% of Twitter users still use twitter.com, so it may be undercounted by as much as a third (but it's hard to know for sure, as many people use both the Web and third party apps).
• Demand Media has risen from #36 to #24. The company proclaims itself to be "the leader in social media solutions."
• Answers.com Sites is a new entrant to the top 50 from a year ago, at #26 in July '09. It's a dictionary, thesaurus, encyclopedia - amongst other things.
• Wordpress is up to #29, from #38 last year.
• Mozilla is up to #30, from #42 last year.
• Break Media is a new entrant at #35. It's a site for "Funny Videos & Funny Pictures".

These statistics show some relatively obvious trends: Facebook is a major major player now, Twitter is hot stuff, and Wordpress and Mozilla continue to make waves.

Also interesting though are the less 'glamorous' sites which are making impressive progress up the charts: Demand Media, Answers.com, Break Media to mention a few of the more significant movers.