1. A method of automatic, computer based creation of a cross-index for a set of documents, the method comprising: accessing a memory to read at least a sequence of words from a document in the set of documents; determining by a processing unit a respective score for at least a subset of words in the sequence based at least in part on word length; operating the processing unit to determine a number of the at least a subset of words in the sequence that have a score greater than or equal to a threshold score; operating the processing unit to determine whether the sequence of words contains a number of words that satisfies a verbosity setting; determining that the sequence of words is a significant phrase in response to determining that the number of the at least a subset of words in the sequence that have a score greater than or equal to the threshold score equals or exceeds a predetermined number and determining that the number of words in the sequence satisfies the verbosity setting; and adding the significant phrase to a cross-index for the set of documents in response to determining that the significant phrase has been found in more than one document in the set of documents.