I have long been a fan of sites that use gamification to teach technology-related skills such as programming languages and database concepts.
I have used various free sites (such as Codecademy and Khan Academy) and premium sites like Code School. Each of these sites have strong and weak points, but all of them have been useful to some degree, and well worth the time and money (when necessary) invested.
A new site that I’ve just recently discovered is DataCamp. This site teaches both R (with which I currently have very little experience) and Python (which I’ve used much more extensively) as they are used for data analysis, especially in the realm of Big Data and data science. This site is not free; it currently costs $300 per year or $29 per month. I have signed up and will begin learning R. As I progress, I’ll report my thoughts on the site – especially as to its value, both from a monetary and time cost perspective.