In the process of troubleshooting a timezone offset issue in my wordpress blog, I discovered to my chagrin that the server time on my Amazon EC2 instance was 6 minutes fast.
I knew a guy in college who would set all his clocks to be 15 minutes fast in order to help him to arrive at appointments on time, but to my understanding the same technique doesn't work particularly well for Linux servers.
(The technique didn't work very well for this gentleman either, to be honest.)
Fortunately, updating the server time is pretty straightforward.
sudo apt-get install ntp
sudo service ntp stop
sudo ntpdate pool.ntp.org
sudo service ntp start
Best practice is to keep your server running UTC time, and then if you need to display or use other timezones to make the appropriate adjustments in your web application.