Check out finance.google.com. It is still in beta. A clone of finance.yahoo.com, with all the ajaxy goodness that comes with all google products. My rating : very good. You can track your portfolio with it. It keeps tracks of your last few stock searches.
One very cool feature that I noticed was the ajax/flash graph which tracks the stock price. On the side of this graph is the list of press releases from the company under study. When you point to each of these press releases, a pointer shows up in the graph, giving the reaction in the stock prize when that press release went out. I think this is very cool. Often times, you will see important press releases going out, and the stock prize going up or down as a reaction to the release.
Check out finance.google.com