Since Google+ is in limited field trial and without invitation any more, there can’t be too many users now, however, someone has listed out who are popular on Google+.
SocialStatistics.com is such a website that will show you the top 100 most popular Google+ users according to their followers:
You can choose to show the first 10, 50 or 100 users on one page, you can filter the list by friends or followers, and you can also click the names to view their Google+ profiles.
In fact, the SocialStatistics.com has listed out more than 100 users, which you can click the "next page" to see. Besides, you can also add your own Google+ profile number or any other user’s to the list and see its rank.
Said by the site creator Boris, the list was created and updated manually with the following way:
I added the first 30 or so myself. Then invited a few friends to check it out. Now it is adding 2 new profiles every 60 seconds…
As you can see from the list, the most popular Google+ user is Facebook’s SEO Mark Zuckerberg, who has made things but never made a post on Google+.
By the way, I am at #244, just above Boris:
How about you?