If you know people who like to worry, here’s a list of new things to worry about that they likely haven’t even considered! See:
10 Disasters That Could End It All At Any Given Second
My favourite is rogue black holes. 🙂
(Thanks to transbuddha.com for the tip and Nasa for the image)
Smart People I Know 
“For a black hole to reach our earth would take thousands to ten thousands of years for its gravitational pull to take the earth. The only way this could happen quickly is if our pull is disturbed by something like a giant meteorite.”
Masterlinks Research Wing D3