Code School - This belongs under all the categories because it has classes in HTML, CSS, jQuery, Ruby on Rails, Ruby, and even Git. It also has courses in R, Sass, Node.js, Backbone.js, and iOS development.
Learn X in Y Minutes - Introduces every language you need to know for web team + more by exemplifying simple code with explanations and comments.
Railscasts - 400+ 5-20 minute videos about different Ruby on Rails topics. Some of the videos require a subscription (like the revised episodes or the ones marked "pro"), but most of them are free to view.