I have been on Facebook for several years now. I like it but I freely admit that postings are not often very significant. It is, however, a nice way to keep in touch with people you know. If you are a creative person, it is one way to share your creations. And sometimes important information is posted.
I am also on Google + but I don't use it. I feel like it is not as sophisticated as some of the other social web sites. That may be changing. And I may begin using it more. But for now, it is not important to me.
I have posted photographs on Etsy, which is a place to sell your work. It has been a while since I used it. I am planning to put some images up on Etsy again in March/April to see if they receive any attention.
I am posting to Trover now and currently have 36 people following my page. I will continue to use Trover as I believe it is an excellent travel site.
My newest ventures are Flickr and 500px. I have set-up pages on these sites and have posted a few photographs. I plan to post more photographs to these sites.
If you are a photographer or if you have a strong interest in photography and enjoy seeing excellent photographs, these sites are good sources.