I often find it hard to answer this question (accurately). Two sources just discovered.
First, the rather obvious Website page at Wikipedia: In February 2009, Netcraft, an Internet monitoring company that has tracked Web growth since 1995, reported that there were 215,675,903 websites with domain names and content on them in 2009, compared to just 18,000 websites in August 1995.
|Netcraft July 2011 Web Server Survey|
With a closer inspection at Netcrafrt, we find this brilliant graphic where there seem to be 108 million global active websites in July 2011.