The last unit of our NetTrek staff training was all about social networking. I've used this type of site for a long time. The first sites I used were especially for writers, but the basic concept was the same. Some sites were simply forums, ongoing conversations among strangers who gradually became online friends. Other sites encouraged members to make personal pages and post stories or poems for others to read and critique. I still find these site to be the most useful and relevant to my life and interests.
Facebook is great for making contact with old friends you've lost touch with over the years. I have almost 100 FB friends and many are people I went to high school with 45 years ago. It's also a good way to keep in touch with relatives you don't see often. One unexpected benefit has been the ability to get to know professional acquaintances a little better. However, FB can easily become a compulsive time-waster with all its games, surveys, and vapid chitchat. I log in very seldom these days.
LinkedIn is supposed to be the way professional people network. I have several contacts there, but I think it would be more useful for younger people who may be interested in career advancement.
Twitter is another site that *can* be a timewaster. It is useful to be able to choose the people you follow and I've found some great links on tweets. The best thing about Twitter is the timeliness. If some is happening RIGHT NOW and you want to find out the details before CNN does - just log in to Twitter and search.
Online Videos and Podcasts: these are most useful when you're trying to learn how to do something. NO amount of words can replace having someone show you, step-by-step exactly how to get a job done. I've used online videos to learn new software many times. Humorous videos are fun and it is NEVER a waste of time to have a good laugh.
