On the lighter side, market sentiments are all around you! When was the last time your mother in law suggested you to buy a stock! That is the best indicator! Also see the adverts in the media, if there are are too many of them asking you to take a dip in the big sea of the markets, sell and run!
On a serious note, Advance-Decline will give you some idea. Moreover, if you are a day trader, who cares for market sentiment?
Cheers!
ss