Jennie and Don are both correct. Both this site, and zillow.com do have a limited amount of information on price changes and length of time on market. But remember that the info source is 3rd party, and is subject to errors and delays.
Here is one example: There's a nice listing in Windham that has had a couple of price reductions. You can see the listing here: http://www.trulia.com/property/1088896216-9-Hancock-Rd-Windh
Scroll to the bottom of the Trulia listing and notice the following price reductions:
11/11/2009 Price change $379,900
11/04/2009 Price change $388,000
10/14/2009 Price change $397,950
HOWEVER, here is the real story:
Property listed for $397,500 on 10/10/09
Price reduction to $388,000 on 10/24/09.
Price reduction to $379,900 on 11/06/09.
Not bad... just a couple of days off, right? What difference can just a couple of days make? In this case, it makes all the difference. An offer was accepted on the property on 11/10/09, before anyone price-watching here or on other sites knew about the price reduction.
Internet sites are GREAT for doing research and familiarizing yourself with trends in an area. And if somebody is dead-set against having a Buyer's Agent work on their behalf, that is for them to decide. However, a Buyer's Agent will IN MOST CASES be the source for the most accurate and up to date information...