PollyVote, the sucessful election forecasting method, relies on combining forecasts. An update of a working paper that describes the PollyVote approach and sucess is available from the PollyVote.com pages here. Oh, and Polly's latest forecast for the US Presidential election is available here.
The Forecasting Principles site summarizes all useful knowledge about forecasting so that it can be used by researchers, practitioners, and educators. The site is devoted to improving decision making by furthering scientific forecasting.