I read this blog religiously during the last election cycle. It used to be independent, now it’s part of the NY Times. His claim to fame is his detailed statistical analysis and resulting accuracy – he doesn’t just look at poll results, he actually looks at the historical accuracy and bias of each pollster and takes that into account when determining what the likely result of the election is.
The end result: in 2008, he correctly predicted 49 of the 50 states for the Presidential election and was 100% accurate for the Senate results. Not bad.
538 is worth reading on just about any polling data.