To get a sense of just how close online home valuation tools can come to estimating a house's selling price, U.S. News had real-estate agents around the country identify homes sold within the past week. Then we compared the selling prices with the values estimated by five leading online sites. The 40 price estimates we gathered were off the mark by an average of 15.5 percent. Only two came within 1 percentage point of the sale price, and one was off by nearly 78 percent. While some buyers may have paid more or sellers accepted less than a house was worth, this exercise shows that while buyers and sellers now have more information than ever at their fingertips, it's still worth checking in with your local real-estate agent before settling on a price. U. S. News & World Report * www.usnews.com * May 7, 2007