1. A method of constructing a domain-specific sentiment classifier for classifying sentiment expressed by documents in a specified domain, comprising: scoring sentiments expressed by one or more domain-specific documents, the scoring comprising: determining that one or more of the domain-specific documents include an n-gram, calculating a score for the n-gram included in the one or more domain-specific documents, and calculating a sentiment score for the one or more domain-specific documents based on the score for the n-gram included in the documents; creating a domain-specific sentiment lexicon based at least in part on said scoring sentiments expressed by one or more domain-specific documents; generating the domain-specific sentiment classifier based on the domain-specific sentiment lexicon; and storing the domain-specific sentiment classifier.