This graph details the Average Days on Market.  This is an excellent tool for both Buyers and Sellers.

Buyers can use this tool in conjunction with the Average Percent of List Price Tool to determine an offer amount and how much time they may have for negotiations.  If the days on market are high, you will most likely have some time for negotiating.  However, if the days on market are low, chances are another offer may come in during negotiations, creating competition and lessening your leverage.  If they are really low, you may want to consider coming in with your best offer.

Sellers can use this tool to determine how long it may take to sell their home and when they should be expecting offers.  It can also indicate when price reductions may be necessary.  If the days on the market are low and you're not receiving any offers, you may want to consider lowering your price.  It is important to listen to the market and respond quickly to get your price where it should be.  In a hot market, days on are a red flag to many buyers.