How about.. The interviewee gets to know what languages, libraries, components of the stack you are using a week in advance. They then can implement whatever they like using those technologies. Then, they present what they made to a technical member who can ask them questions which would show they have developed familiarity with at least some parts of what they use. The more specific the position, the more in depth the questions.. The interviewee can also ask questions back to the interviewer from a more level position.
In this field, this will probably get you lower quality applicants or kids right out of school. High quality applicants have recruiters banging down their doors, and there are always several other options on the table that won't waste a week of their time.
