Google and archive.org both cache/archive sites, however neither of them are fast enough and they don't cache everything.Is there some site where you can input a url and it will go grab it and store it?I find myself in need for proving what was on a site at a time. You can just save as the page, but that isn't very authoritative.
Website caching site
cache
Archive.org has a paid-for service called Archive-It that allows you to harvest your (or any) site as often as you like. Hanzo Archives offer a similar service, target at the corporate sector and legal compliance for data retention.Data from both services should be usable in a court of law to prove what was on a site at a given point in time. Given Hanzo's focus on the corporate sector (the Internet Archive focuses more on the research community), they are probably a better choice for you.