The doormat is one of the first things that people see when they come to your house, besides the outside of your house of course. It should express your personality and sense of style, giving guests a little hint of what they will see inside.
colorful, floral welcoming from Pier 1
beachy welcoming from Pottery Barn
classic welcoming from Ballard Designs
K9 welcoming (and possible warning) from Bed Bath & Beyond
my personal favorite, from Garnet Hill
appropriate for our house, but it may scare guests away, from Wisteria
What's your front door flavor?