URGENT as of 4/9/2014: HeartBleed OpenSSL Vulnerability:
There is a vulnerability in the way most (read: two thirds) web servers protect and encrypt data. This is a very big deal. The bug has been patched, but systems need to be updated.
Read about it in an article by Bruce Schneier here: https://www.schneier.com/blog/archives/2014/04/heartbleed.html
Test out specific websites here: http://filippo.io/Heartbleed/