1. A system for processing search query submissions, the system comprising: a data set that maps individual terms to sets of related terms, said data set stored in a computer memory and being based at least partly on a term co-occurrence analysis, said data set comprising a plurality of entries, each of which maps an individual term to a respective set of related terms; and a query processing system that uses the data set to identify alternative spellings of misspelled search terms of multiple-term search queries, said query processing system comprising computer hardware that executes software.