Keep in mind that a poll is just a snapshot in time. Numbers that are valid one day might not be the next. Plus, there are a lot of people, myself included, who tell pollsters "It's none of your business!" There is a reason that you vote in privacy. However, they are indicative of trends.
Still, I read each poll with fascination, especially the ones for senate here in Pennsylvania. The things that really jump out at me are the number of undecideds this late in the game, and the really high number of people who are not firmly glued to one candidate.
The bottom line is fasten your seatbelts. It's going to be a bumpy ride between now and election night. I am thrilled to see there are a number of places where you can get good, solid information on the candidates and where they stand. A little homework goes a long way, but it doesn't mean anything unless you vote next week.