www.pool.ntp.org

If you have a dedicated Internet pipe, please participate in the NTP Pool project.  It is easy to do.  Go to http://www.pool.ntp.org and follow the instructions.  I joined the pool a few months back.  Here is the server section of the NTP configuration on my Linux box:

server dewey.lib.ci.phoenix.az.us
server ntp3.linocomm.net
server reva.ziaspace.com
server timekeeper.isi.edu
server tick.cs.unlv.edu

You can pick the servers even from servers already in the pool.  I ended up picking some close to me in a network geographic sense.
This is a very useful service and I highly recommend those that have dedicated Internet connectivity participate. The bandwidth requirements are very small and the NTP daemon runs unobtrusively.
On my internal network I sync my local machines using my own timeserver as a time source. I ended up using the broadcastclient configuration which is simple to set up.