I tend to triangulate my data...by this I mean I get redfin, trulia, zillow estimates and then I shave off 20%. Why 20%?...I don't know but it feels good to do it, and this feels about right for me. Yep, I try to use right and left brain thinking and feeling in real estate.
I also look at what was sold in that area (like others have suggested), by looking at the first five properties that compare to the one I am looking at ---the sold prices come up on the right hand side panel. I then take the average of these and compare them to the estimate by Zillow.
Another method I use is to develop a rough metric based on the square footage of the house and the dollar amount that I am willing to pay in my target area. I divide the current sq ft price by 4. Four always seem to be the magic number in business.....Finally, I check the city tax records and glance at these to determine the valuation that the city has determined.
Housing prices are slippery beasts, and in my experience, the pricing of the house can be best understood by the neighborhood in which it rests. For example, the property I want to buy may look sweet, but then by using google maps I can get a visual sense of what the street looks like by dragging the thing a ma jig and going up and down the street. I learned alot about neighborhoods by using good old google map.
Buyer beware...and all that glitters is not gold...and all that jazz (being a little flip with all that jazz, but it sounded good when I wrote it). Hope this helps, and great question....