There are many sites online that provide public opinion data directly. For students, this information is useful for your research. A list of important sources is here.
Here is a wonderful source from the Roper Center on analyzing polls.
A great Political Science blog on Public Opinion is at The Monkey Cage.
Another great one that used to be called "The Mystery Pollster", but is now "Pollster.com".
California polls are mostly run by the Field Poll and PPIC.
Articles/ Stories on Public Opinion
Campaign operatives understand that poll results can influence public perceptions. Here is an excellent story on President Bush's campaign strategist, Matthew Dowd and how he works to manage public impressions of poll results.
Public opinion pollsters from the Gallup, Zogby, and Field Polls discuss their trade with yours truly on Capital Public Radio's Insight October 5, 2004 program here.
Article on the 2004 exit poll discrepancy issue here.
The polls during the 2004 election season behaved strangely - large jumps from poll to poll, different national polls reporting far different results, etc. To sort this all out, check out this article on weighting samples, and this one on "demystifying polls". Ruy Texiera's blog which includes polling info here.
Tracking polls give trends in that poll over time. Here is an example from The Washington Post . Academics were doing overtime trying to predict the outcome of the election. Here's an imaginative analysis by Sam Wang, and another by Jim Stimson with a different methodology
Article on Election poll methodology - a primer put out by AAPOR in October 2004.