Codecademy: Learn the basics of coding, in your browser, for free. Who could resist? Codecademy is a brand new Y Combinator startup that embeds instruction and assessment into one neat, simple package. Check out the overview from VentureBeat. And, if you're hungry for more, you should definitely check out CodeSchool, a fantastic site for learning web technologies like Rails and jQuery (one the EdSurge team has even started using). Not only do these sites help train more code ninjas, they're also great examples of engaging instruction combined with assessments -- something all edu apps strive for.