1. A method for detecting one or more documents that are duplicate or near-duplicate of a first document, wherein the method comprises: obtaining a first document; obtaining one or more additional documents; retrieving a set of one or more document signatures for each document; and detecting one or more documents that are duplicate or near-duplicate of the first document by detecting each of the one or more additional documents that have at least a minimum number of signatures in common with the first document, wherein detecting each of the one or more additional documents that have at least a minimum number of signatures in common with the first document comprises dynamically using at least one of a user-configurable similarity definition and a user-configurable similarity threshold value.