Wow ... there are so many possible answers but I would definitely start with Javascript. Don't learn the whole language, just the "Good Parts". And that would be my first book recommendation - "Javascript: The Good Parts".
With that foundation, you could learn Coffeescript, NodeJS, JQuery, etc. Since you're talking about server side software, Javascript combined with NodeJS will give you both client-side (browser) and server-side capabilities.
You should take a look at the industries you want to join when you graduate to decide what back-end language you should learn. If you're working in a Fortune 500 company you're going to see lots of Java/J2EE. RoR is highly touted but not as wide-spread as you might guess. PHP and Perl are still widely used and there are popular Python frameworks as well.
I agree. As it stands now it would make the most sense to learn JavaScript, then I would learn jQuery if I were you, then move into sockets and node.js. You could then use this one language for the frontend and server-side.
Whoa! ... The Applet is definitely dead, but I included that in my list of languages for the back-end server (and in Fortune 500 environments). It may not be considered cool, but there are still a lot of companies using it.
With that foundation, you could learn Coffeescript, NodeJS, JQuery, etc. Since you're talking about server side software, Javascript combined with NodeJS will give you both client-side (browser) and server-side capabilities.
You should take a look at the industries you want to join when you graduate to decide what back-end language you should learn. If you're working in a Fortune 500 company you're going to see lots of Java/J2EE. RoR is highly touted but not as wide-spread as you might guess. PHP and Perl are still widely used and there are popular Python frameworks as well.
Have a fun summer and good luck!