Want to make sure you get the seating of your choice on that long-planned holiday? Web site Checkmein offers advanced check-in services for a $3 fee.
The idea is that you provide the service with your flight details, and they ensure you're assigned seats in advance (an option that may also come up if you use a travel agent). The service also promises to match you up with people in a similar line of business or help you find someone to share a taxi with at the other end, but presumably that only works if a lot of people try it out.
To be honest, this strikes me as a pretty weird thing to do: many airlines offer online check-in anyway at no charge, airlines never guarantee seat assignments anyway, and if you've got luggage you'll still be queuing at the airport to drop it off. If you give it a go, tell us how it works out in the comments.