11. A system for providing an Internet fax service, comprising: a fax sever to receive messages through fax transmissions on a plurality of direct inward dialing (DID) lines assigned to a plurality of users of the service, respectively, and store raw fax documents derived from the received fax transmissions, respectively, wherein the fax server is to retrieve the users' account information to determine each of the users' subscriber status or subscriber classification including whether or not the user is subscribed to the Internet service; a web server to make the received messages available to the users, respectively, over an Internet and in accordance with the users' account information; and a fax content processing unit to, on a per user basis according to the user's subscriber status or classification, (i) process the raw fax documents using digital character recognition to extract text therefrom, (ii) scan the extracted text to find one or more specified keywords therein, wherein the found keywords arc a subset of the extracted text, (iii) store the found keywords in association with their raw fax documents in a database, wherein the fax content processing unit is to further receive a plurality of requests for message searches, from two or more of said plurality of users, respectively, in accordance with each user's account information, and process each one of the plurality of requests by searching amongst the found keywords that are stored in the database to find ones that satisfy search criteria designated by each one of the plurality of requests, wherein the web server is to further make results of the searching available over the Internet to said two or more of the plurality of users, respectively, in accordance with each user's account information.
17. The system of claim 11 , wherein the fax content processing unit is to further: look up a keyword that is either designated by an owner of one of the received messages or is a found keyword, to find a related keyword, and tag said one of the received messages with both the keyword and the related keyword.