Facebook, like others mentioned, is a great way to stay in contact with family and friends on an ongoing basis. Of course, one needs family and friends to appreciate it's usefulness.
Facebook allows us to share on an ongoing basis, the most current pictures of the grand-kids, not to mention communicating with them. The kids and grand-kids love reading about what we're up to (I hope
) and seeing our latest pictures. ...and that works both ways.
Not to mention finding (and being found by) people I've met and lost contact with over the years.
Twitter? Effin' useless and more of an impediment to a useful life than anythig else, IMNSHO,