I heard Color was using this technology to determine whether people were angry, disappointed, or just waiting for something interesting to happen when using their app.
Actually Color used an early version of this technology to determine how VCs would react to their pitch and tuned it appropriately. This really helps explain both the amount they raised and the confusing quote from Sequoia that "we haven't seen anything this rainy since Google!"
I heard the overwhelming outcome of that experiment was "perplexed"