A common thread on the stagecraft mailing list is announcements regarding where people are traveling and on tour too (as well as food in those locations). I had remembered hearing about a site that allowed people to create networks similar to Linkedin or Facebook that revolved around traveling. If you put in where you were normally, and your trips, you could see who was coming to where you were, and who would be in the city that you were traveling too.
I think this is an interesting idea- it could be great for business, but also good with meeting up with friends who travel alot.
One site that does this is:http://blog.dopplr.com/index.php/2007/12/09/a-dopplr-tour/
The link goes to their intro tour.