Twitter Stats Alexa ranking is #70 as of April 20, 2009
I predict it's next ranking will be in the 40s
The fact that you arrived at this page tells me you have heard of
twitter.
As you can see from this chart taken from
"
Alexa's traffic rankings are based on the usage patterns of Alexa
Toolbar users and data collected from other, diverse sources over a rolling
3 month period. A site's ranking is based on a combined measure of reach and
pageviews. Reach is determined by the number of unique Alexa users who visit
a site on a given day. Pageviews are the total number of Alexa user URL
requests for a site. However, multiple requests for the same URL on the same
day by the same user are counted as a single pageview. The site with the
highest combination of users and pageviews is ranked #1." sites like Google
are #1 Facebook #5
Alexa.com