Request for ideas: What are good examples of good interactive online training (including exercises & quizzes) for how to use web apps?

We continue to look for ways to improve the ability of our users to add value to their organizations. We are always in the process of improving the software tools we provide.

The value proposition for using pairwise and combinatorial tools are huge. The biggest roadblocks we see in adoption are not being aware of the advantages and not being sure how to proceed once the advantages are seen.

We designed Hexawise to be very easy to use. But even so the concepts behind combinatorial testing take some people a bit of time to operationalize. To help with this we offer on site and off site personal training.

We are looking to create some online training to ease the transition into using Hexawise's combinatorial software testing tools most effectively. We would love to know what good examples of interactive online training people have found useful.

Related: Why isn't Software Testing Performed as Efficiently and Effecively as it could be? - In Praise of Data-Driven Management (AKA "Why You Should be Skeptical of HiPPO's")