Over the years I've put my family trees "out there" on various websites...mostly on Rootsweb, but I have a Family Tree Maker website, and I think some of my information is available on Genealogy.com's World Family Trees. I've also been pretty diligent about putting queries on as many county and surname message boards as I can -- trying to reach lots of potential connections.
I'm a big fan of this type of networking -- I really believe that it pays off, and my own experience is that it does. The shortest time that I ever heard from another researcher/cousin was 30 minutes after I posted (WOW!), but often it's been months, and sometimes years until I hear from someone.
Over the last two weeks, I've been fortunate to hear from three "new" cousins, researching some of the same family lines that I am. I'm always excited to hear from anyone who is looking for the same ancestors I am...to hear from three is pretty unbelievable.
After we exchange "how do you dos," we usually agree to share information. Inevitably, as I look over my information, I find that I have gaps that need filling: census data that needs to be added or information from my files that never was inputted. While I'm taking care of this "clean up," I usually do a search on Heritage Quest Online to see if any "new" data is available on this family line -- and if so, I get that information added as well. Pretty soon, the family file in question is as complete as I have sources for, and I'm ready to create a report to share.
It's not unusual for some of the new information (or maybe just my fresh eyes looking at it) to reveal a new clue to be followed, and that's always exciting. Meeting a new cousin and getting a new "research buddy" is great -- the unexpected benefit is that it gives me a good reason to get an old family file back in "new and improved" shape!