We’re a small team at a startup weekend creating a free tool that will help you assess how good you are at coding and show you what you need to learn / get better at to get a job as a developer.
Is this something that you would be interested in?
I think you can test how well someone knows the fundamental concepts of a language. And for CSS / HTML, where there are fewer concepts to learn, you can test language knowledge. The key thing is how well the questions are written. Writing intelligent questions that really probe a learner’s knowledge takes time, skill and patience. And you will need to get good coverage of the whole language so that you can give meaningful feedback about strengths and weakness.
But, if it is well done, it could be a very useful tool.