Solve the non-programming programmer problem. More specifically, solve the problem of obscenely padded CVs swamping the HR department with the result that incompetent candidates fill the interview spaces.
How? Codility.com already made a start on this with online coding tests. But the way it's structured, it'd likely come after the time-consuming resumé inspection. Could there not be a site that handles job listings, applications, AND coding tests? Like the employer posts the job and the site provides an appropriate test. Applicants can send their CV to the employer after they've sat the test.
The cost-saving of not reading all those useless CVs and conducting fruitless interviews should add up to quite a bit for most businesses. I suppose one of the harder implementation challenges would be how to cook up lots of appropriate tests.