Lonely [Australian] PhD Students Use Social Media to Connect with other PhD students.
I can see this being a useful phenomena, especially when you think that all these folks (or half of them) will be in academics when they finish.
Getting into a social connection while students are in school might be a way to increase their circle of influence, especially if those people are in their field.
I also think that reading what recent graduates have to say might be useful. From Tweet to Thesis, for instance, talks about how folks came up with or found their dissertation topics. Sometimes it is when they discovered them.
Should You Go to Graduate School? from a blog at Swarthmore. (This is a very different graduate experience than my MA university. It’s even different than my PhD experience. Does that mean it is only a Swarthmore experience? I don’t know.)
Thinking about Grad School in English? is an excellent discussion put together online by an academic.
I recommend reading all the links. They’re a good way to get a feel for what is going on and what people are thinking on the topic.