Babak, over at Trader's Narrative published a great post about retail option traders.
Here's the chart he mentions and a quote from the post:
Today they were the most bullish they’ve ever been. According to the intra-day activity, they started this morning with a call buying frenzy that took the ratio to 722 calls for every 100 puts. As the day wore on they calmed down a bit but were still buying more than 400 calls for every put. Then finally when the dust was settled, the daily call put ratio for the day stood at 348 - the highest daily close ever since we have data for this metric. That pushed the 10 day moving average to its highest ever as well: 249.
So option traders are even more bullish than they were in the summer of 2007 as the S&P 500 crested. The only caveat I can muster is that we have a limited amount of data since this data series was started in January 2006.