metadata viewer - see the info inside a photo or picture

http://metapicz.com/#landing

Best place to diagnose DNS troubles, mail servers, forwarding to ip addresses etc

http://www.dnsstuff.com/

show your pc screen to someone else

https://www.glance.net/subscribe/Trial.asp?link=persistent_footer

facebook sizes of graphics

http://www.techwyse.com/blog/wp-content/uploads/2013/04/facebook-cheat-sheet-size-and-dimensions-enlarge.jpg