How to get thumbnails on pages
- Using G+ image profile with indirection: http://www.labnol.org/internet/author-profile-in-google/19775/
- meta thumbnail: https://support.google.com/customsearch/answer/1626955?hl=en
- meta og:image (for FB): http://stackoverflow.com/questions/16878007/facebook-ogimage-meta-tag-with-one-image-displays-multiple-thumbnail-previews (supports relative URL)
- Twitter cards: https://dev.twitter.com/cards/markup (image must have absolute URL; creator and site must have leading @)
- LinkedIn: og:image with absolute URL and meta description