Religious Uses of Social Media
There are a number of Buddhist uses of social media that fit within the contemplative/monastic traditions. Probably the most famous is the work at Zen Mountain Monastery, which hosts its own communications center: dharma.net.
They have an online radio station, store, and are working on a "cybermonastery" where, last I heard, they would put up teachings and have a question and answer service.
There is a Buddhist monk on Twitter who sends out daily messages: twitter.com/buddhistmonk
You can also find a list of other Buddhist twitter users here: lodenjinpa.com/buddhists-on-twitter.
I have also observed monastics on Web forums discussing guided meditation practices with other forum members via chat using texts and images from the Web to guide the practice. (There are a great deal of Buddhist texts online in multiple languages).