It's a tough subject; like Val I haven't heard a tonne about it, but I've heard a few bits and pieces.
The idea of psi balls is often used as a form of practice, as far as I know, for forming objects or constructs with your abilities; it's a good way to practice but one that you can't really SEE.
I have also heard of pinwheels being used; the idea is that if you buy/make one of these pinwheels you can practice using your ability to spin them as it's easy to see results and more encouraging.
I think there are at least a few organizations out there dedicated to this stuff, such as psipog.