My brother and I both went (different years) to the Ohio Supercomputer Summer Institute
. While I can't say it was a life-altering experience (we both were already interested in computers and programming; you needed to be to get into the program since applicants have to solve a simple programming problem), it was a great experience both socially and practically—we got to make friends with other geeky kids and do work (and play) on "real" computers (everything at the time was done on SGI workstations running IRIX and we even got accounts on Cray and SGI supercomputers) and do generally cool stuff.
I think that in terms of actual usefulness to the local/regional/educational/technical community though, a longer and perhaps more introductory program would have been better. 2 weeks isn't long enough to accomplish a lot when you're trying to get things done with excited teenagers (it would be hard for anyone), and the fact that the program is limited to somewhat-experienced kids means that while you can accomplish more in that short time you also are not really doing a lot to get new people interested and engaged with technology.