Link Importance

According to one site, they show how long someone cares about a link you posted on Facebook, Twitter, etc.

Here is the graph:

So according to this "study", your links only have a half-life of 3-5 hours.

Study Site

Safer Path

This is a really cool project by some MIT students.  They show you two pictures and you vote, by looks alone, which place looks safer.

Try it out