I know some of you are probably tired of hearing this today, but for the benefits of those who may be out of the loop:
http://www.bbc.com/news/technology-26954540
Basically, a serious exploit called Heartbleed has been discovered in the OpenSSL (Secure Socket Layer), a protocol that is commonly used for transmitting sensitive data online. Many services, especially those where money or private information might be stored, have suggested changing your passwords - Canada's tax agency even shut their sites for the moment to ensure no data leaks. So, better safe than sorry! Good excuse to do a routine password change anyway, which is nice to do every once in a while.