With all the Web 2.0/Social Networking noise we are all used to "virtually socialize", but now you can use it to do more and improve the quality of your trips.
The site IDTGV and Co (only in French so far) allows you to enter your profile and hobbies. Then when you do a reservation for the TGV (high speed train) you can match it up with other travelers. I have not tried this service yet since I am mainly traveling in the north of France but I will for sure try it as soon as I can.... Let me know if you have tested it.