Your understanding of the housing market hinges on two factors: your ability to obtain accurate data (difficult), and your ability to make sense of said data (more difficulter). Helping you on both fronts, HomePredict.
Based in South Park, HP collects and shares the sort of super-accurate data devious real estate agents keep from you, and then tells you what it all means via a user-generated value-prediction system. To begin, enter your criteria of interest (zip/house vs condo/price range); HP'll then tenderly probe every related listing to paint a picture of the previous quarter: median selling price, median price per sq ft (to inform size vs location value), and the number of days properties sat on the market doing nothing but unwillingly hosting teenage pharm parties. Assuming all this means nothing to you, the other half of your screen'll show an average of how other users interpret the data, weighted to favor prophets with a proven track record; an extra click gets you individual user's assessments, at which point you'll know who to trust, and who's clicking "higher" to make his own house worth more.
If HP gets you amped enough, they've just rolled out a sister site, ProOffer, that lets you post exactly what/where/when you're looking to buy or sell, then sit back as agents draw up targeted proposals -- honesty that for them is the most difficultest thing of all.