I have a pet theory that if a neuro-plastic state is induced through various substances and "training" is performed (stenuous mental activity, brain entrainment, CET, learning new skills, languages, etc) it will lead to a permanent increase in intelligence and decrease the time it takes to become proficient in the "training".
I'm thinking of things like:
1. Idebenone, Hydergine for NGF.
2. GH/IGF1 for increased proliferation/regeneration.
3. Prostaglandin analogues.
4. SSRIs for stimulation of neurogenesis in the Hippocampus.
Any one with any ideas - let's throw this one around a bit.
Tracer
Like your idea, and have guinea-pigged this one on myself in a fairly unstructured fashion. If you'd be interested in doing this in a more organized test, I would be willing to help (and be a volunteer). We could generate some fairly useful anecdotal evidence...
It would probably work best if several different types of "training" skills were selected from different categories of capacities (i.e. something like juggling + a balange exercise for coordination, some purely brain-oriented task like Su Doku or logic puzzles, a couple of things for spatial reasoning,, couple for linguistic ability, etc).
Another idea: what about combining the things you have mentioned with practices that are meta-level support for brain function (that is, not support for a specific task, but for tasks in general). I don't know if you have heard of "Image Streaming" by Win Wenger, but it is a technique that works on "pole-bridging" - basically an exercise that forces that different hemispheres of the brain to work together, thus forging new cross-brain connections. Wenger originally published this in a fairly scientific study of intelligence increasing (called
How to Increase Your Intelligence, now unfortunately out of print) and has re-published it under
The Einstein Factor. The first book is much better (less pps-culture appeal), containing more raw data and anectoted research, and makes the claim that subjects averaged a quarter of point increase in IQ for every hour they did the practice. If you can find a copy of the first book, there are many other practices that are described and fairly well documented.
Again, I'd be interested in participating in any kind of impromptu group study of the effects of brain enhancing supplements/drugs/practices on training and learning. In fact, it seems like the type of thing that this is the perfect venue for.