Hey HT--Yes, I look at a variety of surveys and indicators to measure investor sentiment. But it's not an exact science by any stretch. I watch the AAII survey (which I saw is very bullish today), various put/call ratios, the sentiment survey here, various consumer sentiment surveys, Mark Hulbert's articles on sentiment found at Marketwatch, some of the writers at Minyanville who discuss sentiment, etc. I also try to get a feel for what the media (both general and financial) are saying about the markets. Reading the headlines of articles can help there.
The difficult part is that people are naturally drawn to investors/gurus/writers who support their view. That makes it hard because I don't want to get entrenched or emotionally attached to a bullish or bearish position. In other words, if I'm bearish, then I will have a tendency to listen to people who are also bearish, and I'll poo-poo the bulls. (And the opposite is true, of course.) To counteract that, I try to read a decent amount of articles that disagree with my outlook.
The key for me is to do my best, stay humble, and try not to get emotional. I realize that I'm going to be wrong a LOT of the time--so it shouldn't surprise me when I'm bullish and the market tanks, or when I'm sitting in cash and the market spikes. Also--big picture: money is nice, but it can quickly become an idol that enslaves you. It can never satisfy. Trying to build your life on making money leads to hellish misery. (I speak from experience.) That was a lot more than you asked for, wasn't it!