Sure, Yahoo Finance rocks. But plenty of other, smaller sites offer good data for the online investor. Yesterday's San Francisco Chronicle outlined seven of them.
In Harry Domash's piece, most of the seven were new to me, though I had written about one of them (tickerspy.com) here previously.
Domash has a good range of sites, such as a site that tracks Chinese companies that buy a U.S. listed company instead of going through an IPO, and another that lists potentially undervalued stocks based on its intrinsic value and a "margin of safety." He also has his personal favorite for that investment must-have, price charts.
Here's the online version of the story, with links to each suggested site.