This list is certainly not definitive but if you are not in the Computer Sciences by way of study or profession then the info below should help you get started...
Codecademy: Learn to code
Lessons to learn to code interactively.
Learn | Code.org
Choose from 3 activities designed to give you your first experience programming.
Code Avengers: learn to code games, apps and websites
Hurricane Electric Interactive Programming
Interactive Programming Courses. Perl · PHP · Ruby · Python · SQL. Web Development Courses. HTML · CSS ...
Interactive Python Tutorial
LearnPython.org is a free interactive Python tutorial for people who want to learn Python, fast.
RubyMonk - Interactive Ruby tutorials
Free, interactive tutorials to help you discover Ruby idioms, in your browser!
Code School: Learn by Doing
Code School teaches web technologies in the comfort of your browser with video lessons, coding challenges, and ...
List of interactive programming websites - Reddit