Sorry I won't be able to post a sample (proprietary software at a financial org, behind a firewall and our solution is still being fully tested), but I wanted to share how we implemented this since you all inspired a nice idea.
We have a very robust, yet tough-to-use Online Policy Manual maintained by the legal/compliance types. Basically an internal wiki of all the policies and archaic processes you might need in the org. HUGE. COMPLEX. And unfortunately unruly.
But 100% necessary.
So, we developed training to help folks navigate using different methods (different types of searches, main navigation, etc...). We have the typical learn (info), try (guided practice/sim), but for "prove you know it"- we used the NEXTCHA design.
We pose a challenge for folks to find X using a certain method. And bring up the live policy guide, noting that they need to copy/paste the first 5 words into the NEXTCHA.
You aren't going to pass this one if you don't actually perform the task.
So now, we know folks are actually performing this before going any further.
Thanks all for the great idea. We had the scavenger hunt concept on our mind for a while, but this NEXTCHA was just too simple to ignore in how to implement a nice, quick design on the concept.