From those that have taken them, which of the coursera/udacity/EdX courses are really really good? I go to the sites, get excited and register for everything but I know focus would mean I'd stick with them.
6.002x is an amazing course (it's the only EdX course that has run so far, but they have a great platform).
The Udacity courses are generally slightly easier (e.g. they avoid the low-level details of the maths), but I really enjoyed CS373 (Programming a Robotic Car) and CS212 (Design of Computer Programs).
The Coursera courses are a little hit and miss in terms of quality, but Quantum Computing and Design and Analysis of Algorithms are both very good.
