If you had to ask me (and by reading this, I'll assume you're asking me), the next void that will get filled on the internet is the need for a private community.
Facebook was initially just for college kids and college kids shared college things on it. Then they added on high schools and after that they opened it up to everyone. So where it used to be you were sharing with 30 people, you're now sharing with everyone from your high school, your family, your college professors, fictional cartoons, and basically the whole rest of the internet. Anything you share you're sharing with everyone you know and I'm guessing that not everyone will appreciate that hilarious photo of the foul-mouthed belligerent anteater.
So people move to other services. Services like twitter. I like twitter. I'm on twitter. I interact with about seven people on twitter. And it's nice and my updates are protected.
But twitter could soon become popular among a wider audience which will, for me, just dilute the quality. It's not that I'm going to miss out on a fatty paycheck, be sued for defamation, or get fined by the NBA, it's just everyone needs a place where they can interact with a small group of people rather than everyone they've ever met. Plus I don't really care if the girl that sat two rows up from me in eighth grade is excited about the nice weather today [but twitter friends, I will happily hear it from you].
So while all this connectivity is cool, tell me about a community where you can easily and selectively share with select people and I'll get excited.