When you enable ntpd in /etc/rc.conf like so

ntpd_flags="-s"		# for normal use: ""

if your network interface isn't up, ntpd can
hang for a while before the system finishes
booting. Some say they've seen it hang for up
to half an hour. Instead of the entry above,
you can use:

if ifconfig fxp0 | grep 'status: active' >/dev/null 2>&1
then
        ntpd_flags=-s
else
        ntpd_flags=NO
fi

If you've got more than one interface, for instance,
maybe you plugged in your 'wi' PCMCIA card before booting,
you can do this:

if ifconfig fxp0 | grep 'status: active' >/dev/null 2>&1 ||
   ifconfig wi0 >/dev/null 2>&1
then
        ntpd_flags=-s
else
        ntpd_flags=NO
fi

That way, if either one's up, ntpd will be able to set the
time. If not, the script will set ntpd_flags to NO and
booting will continue.