Best real estate online "source" to research the market?

[Todd Hensy]

Hey guys,

What is the best online real estate resource to study real estate markets?

How can I be a dealmaker if I don't know the RE market? I would like to invest in foreclosures, apartments, or a SFH. How can I do that if I don't know the market or if the market is hot or not? Plus I would like to know where the hot markets and down markets are across the country?

Good sources that are reliable? Realtytimes?