Level 2 stock quotes can reveal the market breadth. They can also be used by MM. For some information on how to use them, check out this link:
http://www.investopedia.com/articles/trading/06/Level2Quotes.asp
So, where can you get your hands on this Level 2 Quote stuff? Well, your online broker probably has them. Some places are free, others charge a premium or give them as a bonus to active traders.
e-trade Canada gives free level II, and so does Credential Direct Canada if you are tired of the banks, hehe