Reliable Time Protocol Server Online?
NIST still provide some TIME (RFC-868) services, alongside NTP and DAYTIME.
Just pay attention to the notice in green at the bottom of the page.
If you have a Unix-like box around, I believe it should be possible to set up your own TIME server fairly easily - Wikipedia suggests that the daemon is installed by default on many distributions, requiring only that you enable it in your inetd.conf. The time on the Unix box could be kept in sync with NTP.