MyFonts

Perhaps a bit more specialist than usual, but if you have ever come across a piece of design on the web, or out there in the real world, with a fontstyle you would like to emulate, Myfonts is a useful website that will identify the fonts used for you.  There is even an app for the iphone, so you take a photo of the font anywhere, to identify right there on the spot. 
(Without becoming too geeky, I think I am right in saying Gill Sans MT, available in Word 2010, is not a million miles away from the London Underground Johnston font, but correct me if I am wrong)