This is just my opinion- but I think that Downhiler 2010's friend has it right. Based on conversations I have had with some friends in the college admissions world, I think that these are pretty much not viewed as anything other than something that middle class kids spend their money on. So while they might be intellectually interesting to attend-don't expect a college admissions team to view it as some kind of distinguishing feature when considering your application. The exception is kids going to a summer program that the school that they are applying to runs itself (for example Mass Maritime and Norwich both have summer orientation programs) which at least demonstrates to the school that you are very interested in that particular school. Again it's my humble opinion, but if you want to set yourself apart- do something that you can't buy your way into- volunteer or get a job working with people in something relating to the major you want to go into; Volunteer at a homeless shelter or old folks home; Or for that matter- get a job where you have to work hard and are the best temp that the boss ever had.
So- my advice as a Dad whose son is in school where he wanted to go, on someone else's dime- if you are going to one of these because the subject and the location sounds interesting and you have money to burn- well that is something (and Georgetown is a cool place), but take the NSLC sales pitches with a whole bunch of grains of salt.