I stumbled upon Ning yesterday during my career search. Do you have a passion, profession or a hobby? There is most likely a group that shares your passion on Ning: www.ning.com or you can start your own in minutes without programming knowledge. Check it out, or read more here: http://www.techcrunch.com/2007/02/26/ning-in-full/comment-page-3/
A Day in the Life of a Presson…
Co-discover Interesting things :)
A Day in the Life of a Presson... 
How many social networks really are needed? My space, facebook, linked in, ect.. ect.. Turn off your computer, make a call, write a letter, or visit someone in person… That is a lot more meaningful to some.
I agree to a point, but how do I find others who enjoy a job or Hobby or are looking for wark without a social network of some sort? Also, there is a group of friends that I keep in touch with in person, phone etc. But there is a larger number of people that I want to stay in touch with, but it would be with little to no frequency unless there was a social network to keep in touch.