My friend and I are planning to build a website that draws from a database back-end (PostGres, MySQL, etc). What would be an easy, non-Microsoft way to make an easily extendable, interactive website? It's not that we have anything against Microsoft; it's just that the web servers we could use only has Linux on them. Thanks in advance!
I'd recommend going with something like Drupal and extending where necessary.
Learn PHP for the server side scripting, it is the most widely used Server side language by far and it's very simple to communicate with an SQL database with it.
I'd suggest (unless you're really into building your own CMS) using a pre-built "framework" like Drupal, Joomla, or WordPress as a base and then extending it as you need to.
Drupal, in particular, is very flexible.
That said, it largely depends on what your "interactive website" is going to do, doesn't it?
I would DEFINITELY use Ruby on Rails. I've been developing web applications for some time. I started with PHP/MySQL and I will never go back after using Ruby on Rails.
Take a look at some screencasts and I think you'll be amazed how much can be accomplished with very little code.
If you have shell access and a wider control of the server, Ruby on Rails or Django (python) are pretty sure choices. Both are frameworks that aim at rapid development with easy-to-understand code and both have some easy to use ORM (Object-Relational Mapper) for database abstraction.
If you have less control, I'd advise on PHP simply because deployment is the easiest of probably any language used in web development out there.
Personally, I'd go for django, because it has a wider proven track record of reliability - there's been some horror stories of ruby/rails eating up all your memory in no time. Furthermore, even though Ruby is a really nice language, python is more mature. You could also reverse it and say that Rails is more mature as a framework than Django, but I still think django has most (if not all) of what you need.
On the far ends of the scale we have all the Java tools. I wouldn't recommend them out of the box for new developers, but if you have some savvy Java developers on your team, this might be the option for you.
There's a different tool for every task, but nothing weighs as much as developer experience.
If you want to avoid a steep learning curve, I'd recommend the traditional LAMP (Linux, Apache, MySQL, PHP) model. You will find an incredible amount of resources with PHP/MySQL combination to help you get started.
If you want to try something besides PHP, I'd first recommend Python. I find it a lot easier to work with than Ruby on Rails. There are a good amount of libraries and resources available to you with Python; slightly more than Python.
But in the end, it depends on how quickly you want to launch your website and what languages you're already familiar with.