1. A method for use in a computing system containing a database of available documents that are to be searched using one or more key terms, the method searching the database to identify a plurality of documents for subsequent presentation in a ranked order, and comprising: using a ranking algorithm on documents identified by an inverted index as containing one or more key terms to create a special list for at least one key term, the special list for the at least one key term ranking a predetermined number of highest ranked documents identified in the inverted index as containing the at least one key term, wherein the ranking algorithm ranks documents in the special list according to a form consisting of Rank=(tf/K+tf), where K=dl/avdl, and wherein tf is occurrence of a key term in a document, dl is document length, and avdl is an average document length; appending the special list to the inverted index and storing the inverted index on one or more computer readable storage medium, the inverted index having separate portions for each key term, and the portion for the at least one key term including: a listing of documents that contain the at least one key term; within the listing of documents, occurrence data for each of those documents; and the special list for the at least one key term, the special list being separate from the listing of documents; at a server computing device, receiving a user request for a search of the at least one key term, the user request also including a speed and thoroughness level for searching for the at least one key term; at the server computing device, accessing the inverted index and the portion of the inverted index corresponding to the at least one key term; at the server computing device, searching one or both of the inverted index and the special list for documents containing the at least one key term, such that: when the speed and thoroughness level is a minimum thoroughness, only the special list is searched; when the speed and thoroughness level is a maximum thoroughness, all relevant entries in the listing of documents in the inverted index are searched; and when the speed and thoroughness level is between the minimum and maximum thoroughness, the special list is searched along with only a portion of relevant entries in the listing of documents within the inverted index.