In terms of my job, one of the single most important (and luckiest) things that I did early in my computing days was to start learning the programming language Perl. I had done a little HTML and gotten some JavaScript to work before, but Perl was the first language I really started with. I've often heard Perl referred to as The Duct Tape of the Internet. That was probably more the case in the early days of the web than it is now. Lots of other specialized languages  and tools have cropped up to specifically address web site programming, but Perl still gets very steady use from me in publishing my other site. One case in point is the transition I'm currently working on to move from one production partner to a new one. Ideally, I would have had about eight months to complete the transition, but I wouldn't expect more than six. What I got was a little over three. Suffice it to say that without Perl that time line would have gone from incredibly tight to impossible. There are just so many moving parts that without Perl's ability to quickly create a very powerful program that can do just about anything we would have had to abandon several features on our site. What's even more amazing about Perl is the fact that it's free. It comes install on virtually every Linux OS and can be had on Windows with a quick download. Once again going to show that sometimes the best things in life really are free.