Now everyone knows that ntp is a good thing, but something that I've found useful recently is pool.ntp.org

A common problem when setting up ntp (or the Windows net time command) for a small or home network is finding a suitable stratum 2 (or lower) public time server to sync to.

pool.ntp.org uses DNS round robin to share the potential load over many time servers, they even suggest that anyone with a static ip address and a permanent internet connection should join the project, I'll add that to my to-do queue...