One of the customs associated with a Papal visit is the granting of "plenary indulgences," or special forgiveness of sins, to Catholics who turn out to see the Pope -- and according to a recent decision by the Vatican, that privilege now extends to people who witness the Papal visit virtually, via social media.

Facebook users drastically underestimate how many people their content reaches via the social network, according to a new study from researchers at Facebook and Stanford University, titled "Quantifying the Invisible Audience in Social Networks."

There is so much going on in the social media universe that it is pretty much impossible for anyone to keep up with all of it. But sometimes you can get an overall picture of what's going on -- or at least, a random sample hinting at the sheer variety of the space -- through the simple mechanism of a Google News search. Today yielded up an especially entertaining (and sometimes bizarre) slice of social media life, so I thought I would just share some headlines. Enjoy!

Okay, now I think I've seen it all: there is a new social network, Bootifly.com, devoted to your butt (well, not just yours, but rather any and all posteriors -- our collective derriere if you will).

Over the last few years Egypt has become something of a laboratory and proving grounds for social media applied to political activism. Social media clearly played a big role in enabling ordinary Egyptians to organize protests that eventually brought down the dictatorship of Hosni Mubarak in February 2012. But social media has been much less effective in achieving what is arguably the most important goal of any revolution: reestablishing order through effective government with broad popular support.

Who would have thought that a collection of digital miscellanea might not be the best way to judge an individual you've never met in person? Oh right, lots of people with common sense. But apparently not employers, who are apt to pass on well-qualified job candidates because of perfunctory or misdirected glances at their social media profiles.

While Facebook may allow online influencers to reach large numbers of people, email is more efficient, as a larger proportion of the people reached via email actually become customers, according to a new study of social referral marketing campaigns by SocialTwist, titled "The Connected Consumer: Brand Advocacy Trends from 100+ Social Campaigns."

If you wanted a good laugh today, nothing can beat the news that Michael and Xochi Birch, who founded Bebo back in 2005 and sold it to AOL for $850 million in 2008, recently repurchased their 8-year-old creation for $1 million.

While most people can use LinkedIn, some professions pretty much require their own dedicated social networks: domains like healthcare and law enforcement are so highly specialized -- and so liability-prone -- that there's not much a layperson can really contribute in terms of professional insight.