I was checking out an article posted on Digg.com touting Digg as being the 4th most popular site based on the number of sites linked to it. The author of the post decided to use links popularity as the way he measures site popularity as opposed to Alexa's site traffic rankings. He stated that the Alexa ranking data is gathered from the ten million or so users of the Alexa Toolbar. And although the active number of users of the toolbar is probably a fraction of the overall would still be relevant, he wanted to use a broader measure and went with number of links as counted by Google. The problem is that link-counts differ from search engine to search engine. So where Digg gets 120,000 links counted on Google, MSN counts 590,412 links, Altavista counts 1,100,00 and Yahoo! comes up with 9,620,000 links! That's a huge spread (you can find out the link counts from these search engines for your site by clicking here and entering your url). So you gotta ask just how accurate are any of these methods for finding out how popular your site is?