I've been hearing a lot about Git which is a 'free and open source distributed version control system' (according to Git's official web site), so I dug in a little bit:
There is a lot of great documentation on their site, so I read a little bit. It was a bit confusing to myself not having any background in any kind of version control systems. However, I started to appreciate the potential power of it, so wanted to learn more. I happen to have a Lynda.com subscription, and they happen to have a 6 hour course on it. Over the course of several weeks, I completed the course and now have a greater understanding of it. I just started using it at work (I created and maintain the company's Intranet and Extranet).
The real power of Git is how it allows multiple people to work on a single project. They can all be at the same physical location, or separated physically by thousands of miles. Git is very fast, powerful, takes up little space (the 'program' itself, and the revision history), and to use the basics, it's pretty easy to get started. Oh, and it's available to Linux, Mac and Windows...and did I mention it's free?
I highly recommend it to any kind of coder - web developers, application developers whether you're just one person or on a team.