The next Mark Zuckerberg

To Karl Jacob, there's not much value in knowing what your friends are doing right now.

"What's happening right now is only of little use because the amount of time you have to do something about that is very limited," Jacob says.

That's the thinking behind his new app, Hangtime. It searches through the open graph on Facebook and other online sources looking for what your friends are planning to do in the future, and then Hangtime creates a calendar for you.

Hangtime ranks the events by how popular they are among your friends, so you can change your plans accordingly. It brings new meaning to the phrase "social engineering."

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