Two excellent resources about multiple imputation and missing data:
Joe Schafer’s Multiple Imputation FAQ Page gives more detail about multiple imputation, including a list of references.
Paul Allison’s 2001 book Missing Data is the most readable book on the topic. It gives in-depth information on many good approaches to missing data, including multiple imputation. It is aimed at social science researchers, and best of all, it is very affordable (about $15).