I don't bother with facebook, twitter, linkedin et al because it does not serve my purposes. It is sort of like working a part time job and not getting paid for it. I don't see anything that productive coming out of it. Though, I am considering using alternatives like Quitter, Diaspora, among other GNU social alternatives. However, they do seem to require a lot of effort and am not sure I want to invest in my time that way. Things like Vimeo and Flickr make more sense (to me) as you can work on video and image stills and share with a community to get critiques on your work. As for employment, while some may not hire you if you don't do social media, people also lost their jobs because of social media. It is a sad commentary that people may not hire you because you don't have a bloody linkedin account. I've been spammed mercilessly by linkedin and recall a time they used to go through user contact lists on e-mail clients. (come to think of it, that is how they spam people...) I understand why linkedin does this, but it is also terrible etiquette.