Some very interesting stats on a Royal Pingdom post. Here's a selection of those that particularly interest me:

Email

• 90 trillion – The number of emails sent on the Internet in 2009.
• 247 billion – Average number of email messages per day.
• 1.4 billion – The number of email users worldwide.
• 100 million – New email users since the year before.
• 81% – The percentage of emails that were spam.
• 92% – Peak spam levels late in the year.
• 24% – Increase in spam since last year.
• 200 billion – The number of spam emails per day (assuming 81% are spam).

Social Media

• 126 million – The number of blogs on the Internet (as tracked by BlogPulse).
• 84% – Percent of social network sites with more women than men.
• 27.3 million – Number of tweets on Twitter per day (November, 2009)
• 57% – Percentage of Twitter’s user base located in the United States.
• 4.25 million – People following @aplusk (Ashton Kutcher, Twitter’s most followed user).
• 350 million – People on Facebook.
• 50% – Percentage of Facebook users that log in every day.
• 500,000 – The number of active Facebook applications.

Images

• 4 billion – Photos hosted by Flickr (October 2009).
• 2.5 billion – Photos uploaded each month to Facebook.
• 30 billion – At the current rate, the number of photos uploaded to Facebook per year.

Videos

• 1 billion – The total number of videos YouTube serves in one day.
• 12.2 billion – Videos viewed per month on YouTube in the US (November 2009).
• 924 million – Videos viewed per month on Hulu in the US (November 2009).
• 182 – The number of online videos the average Internet user watches in a month (USA).
• 82% – Percentage of Internet users that view videos online (USA).
• 39.4% – YouTube online video market share (USA).
• 81.9% – Percentage of embedded videos on blogs that are YouTube videos.