I haven't used this yet, but thought I'd go ahead and pass it along since so many people wil be traveling for the holidays:
If you're going to be traveling solo in a few weeks for round two of the holiday season, worth checking out is the Boarding Project. It's a social service that uses Twitter to help you meet up with others at the same airport. To use it you simply tweet #boarding along with your airport code. It'll send you a reply with a link to the other Twitter users who you can message directly to meet up with.
Boarding's system does not require users to sign up for anything. It also keeps an eye out for any FAA or IATA airport code mentions in public tweets, and will send a reply to that user urging them to check in to see who's there.
The service plans to make money by offering special coupons to travelers, which could be shaped around any contextually relevant information from their Twitter stream.