Welcome, or something like that.

Once upon a time, just about all doormats came in three varieties. There were plain mats, mats that said "welcome", and the fancy kind that had your family name on it. Now, you have ways to welcome people to your door that make a statement about who you are.
This mat is too clever by half. Especially if your name is really Matthew.
Perfect for a computer geek, this doormat says "There's No Place Like 127.0.0.1" which is, of course, home.
To you, this may appear as a nice but boring pattern on a doormat. To a geek, it spells out "welcome" in binary language. It's an inside joke that will amuse you as you wait outside.
More clever doormats, after the jump.
Another twist on the inside joke comes from the Navy. This doormat spells out a message in Navy flag code, but it doesn't say welcome. It says "Wipe your feet!" Which would actually be a more useful message, IF you understood it.
If you are a geek, but your guests aren't, consider the old-fashioned "welcome" with a twist. Here's an electro-luminescent doormat complete with motion sensor that triggers the word to light up when someone is detected. They'll either smile or run screaming for the hills.
To take that idea a bit further, how about an animated Space Invaders doormat that runs on AA batteries and uses flat panel LEDs? Too cool.
The outdoorsman with this doormat makes it clear that he might not be home for a particular reason.
You might make your visitors a little nervous with this one, or else they'll just laugh, like I did!
I once labeled this "the best doormat ever". A perfect gift for some of my more, um, adventurous neighbors.
This versatile doormat can be positioned to tell visitors how you feel on any particular day. Do you want them to "come in" or "go away"?
A hostage situation printed on a doormat means you'll open the door to smiling guests.
I haven't been able to make my mind up which I like best, but with two young children, I should just get one that says, "Wipe Your Feet!"