Google offers a little Toolbar that provides additional information about the displayed website, including the PageRank value that indicates how "important" the website is in Google's eyes (and that's said to be used to calculate the relevance in Google searches).
Here are some values that I looked up:
www.amazon.com: no value
www.wikipedia.org: no value
www.orf.at (Austria's national TV broadcast station): 7/10
www.freesql.org: 5/10 (but currently no content)
There's only one website that I've found with a value of 10/10: www.apple.com.
However, it's great to see that the relevance of MySQL's website is among the highest of all websites of the world.