third-party datestamp site?

James Tauber (
Wed, 17 Mar 1999 21:21:58 +0800

Here's an idea for a site:

You submit a document and it returns a date-dependent digital signature for
the document for a small fee.

Another party can submit your document with the date it was supposed to have
been submitted on and the site verifies it.

Third-party date stamping over the web. Does such a beast currently exist?
Or is this stupid?