A site of mine is going to be featured on a very popular tech blog. I already upgraded my server to handle the traffic. What other things should I be prepared for?
Apart from the other fine suggestions so far, you might also want to run your site through some benchmark tools like Google's Page Speed and YSlow – if you don't understand or want some more information about some of the results, there are some blogs that go into more depth with explanations – to see if some simple changes to what you have could translate into some cheap performance gains without throwing more money and hardware at the problem.
Instead of generating pure static pages as John Conde recommends you could set up a cache like e.g. Varnish. Varnish is then taking all the requests and caches them for later use. This way the web server has to handle a lot less requests.
What did you upgrade to handle the traffic? You should put it onto an ec2 server with scalr to bring up extra server instances if traffic increases plus add a load balancer