Seeking methods for on-line access of historical data

I am looking for methods for saving a historical record of database information and having it available on-line, simultaneously with the current information. As I work out the details I get the distinct feeling that someone out there must have been down this path before. Anyone out there worked on this problem and have some advice, and how your solutions fall in the time-versus-storage spectrum. Bill Gale bgale@portal.hq.videocart.com