The President and CEO of Prudential Douglas Elliman, Dottie Herman , is a big believer in publishing market data to create more transparency for consumers in the market her firm serves – Manhattan to Montauk.
Other reports we prepare can be found here. 
A report excerpt
…For the second consecutive quarter, listing inventory has declined in addition to the contraction in the number of sales over the same period and the prior year quarter. There were 20,730 properties listed for sale at the end of the current quarter, down 0.3% from the same period last year with 20,801 properties listed at that time. The number of sales slipped 3.4% over the same period to 4,427 sales, from 4,584 sales. The stabilization of inventory combined with the decline in number of sales suggests that there are fewer Ã’casual sellersÃ“ with many opting to wait until housing market conditions improve before listing a property. The contraction of credit and the current recession continue to limit the number of sales, placing downward pressure on price trends…
The media coverage of the report is available here  as they were obtained (in no particular order).