What Facebook did for college students, several new social networking sites may be doing for business travelers. Skylounge.com links up execs on the road—those who already know each other and those seeking new connections. The average age of members is 35 and the majority of members hold management positions. Dopplr.com shows where your trips intersect with your friends’ trips. You input your plans, friends input theirs. You’ll never cross paths unknowingly. TripLife.com starts with the flight—to let you know if, for example, someone you should know in your industry is on the same plane—and expands from there to your hotel, convention, etc.