CBOE VOLATILITY INDEX - VIX, PUT/CALL RATIO, EQUITY-ONLY PUT/CALL RATIO (put/call ratio only available since Jan. 3, 2000) (equity-only put call ratio only available since Jan. 8, 1997)
It is important to note, however, that the QQQ option volume can distort the data quite strongly at times. So take these numbers with a grain of salt.