The reunion problem
The internet should make this easy. Six degrees of separation, social networks, online profiles and Google should all make it automatic.
It's not, for a few reasons. First, people rarely surface all of the details of their life online (or even in Facebook). Most of my readers, for example, have no clue about the undefeated hockey team I was on in 1973 (of course, the only goal I scored was on my own team, but that's a story for another day). The second reason is that spammers would be all over this information if it were easy to find. If one could email every single Facebook user who came from Cleveland, the thing would fall apart. For good reason, permission to contact the right people isn't easy to get.
While shouting about a reunion from a blog might work, it's not particularly efficient, is it?
So, what would I build? It seems to me that the two steps are enumeration and contact. First, you need to list everyone you're trying to reach, and then you need to figure out how to contact them. If there were a simple piece of web software available (basically a smarter wiki), you could reach out to the 20 or 50 or 500 alumni you already know, point them to that and get them busy enumerating the list. How many people can you list from cabin 7? Who's missing?
Once you've got the list, put the six degrees thing to work. As each person on the list gets contacted, you can put a mark next to their name. As the list of the uncontacted gets smaller, it's easier for people on the fringes to focus on who they know that might know the person that needs to get reached.
My guess is that the solution already exists, but a bit of googling failed to find it.
And, if you're a Camp Arowhon alum (or you know one) and want to hear about the 75th reunion, drop a note to Marnie asap.
[Scott has a solution, but it's not quite as bare bones as I described.]