Python
Python is a one-stop shop. There's a Python framework for pretty much anything, from web apps to data analysis. In fact, WordStream is written in Python! You're the best bud. Python is often heralded as the easiest programming language to learn, with its simple and straightforward syntax. Python has risen in popularity due to Google's investment in it over the past decade (in fact, one recent study has shown Python to be the most commonly taught programming language in U.S. schools). Other applications built with Python include Pinterest and Instagram.
C++
If you saw C++ on a report card, you'd be pretty bummed. Maybe a bit confused, too (is it actually a B-?). However, C++ is not the bizarrely bad grade it seems to be. It's often the first programming language taught in college (well, it was for me 10 years ago). I thought it was a nice "in-between" language in that it was object oriented without having to be fanatical about it. It was also low level enough to be close to hardware, but no so low level that you had to do everything manually. Because there are so many C++ compilers, you can write stuff in C++ and have it run pretty much anywhere.
PHP
PHP (which stands for Hypertext Preprocessor, if you care to know) is often used in conjunction with dynamic data-heavy websites and app development. It provides a ton of power and is the beating heart of monster sites like WordPress and Facebook. What's really cool about PHP is that it's an open-source language, so there are tons of free pre-built modules that you can grab and modify to get your ideal results. PHP is also on the easy end of the learning spectrum, simply requiring you to embed the code within HTML. PHP is a must-learn language for aspiring web developers.
Javascript
JavaScript (which, confusingly, is not at all related to Java) is another favorite programming language because it's so ubiquitous on the web--it's basically everywhere. JavaScript allows developers to add interactive elements to their website, and its presence is felt across the internet. Javascript is my personal favourite I guess. I really have a hard time choosing the best.