There is a great e-book called The Master Plan you can purchase from
http://www.seo2020.com/ by Charles Hilfin. It explains in great detail how to research keywords for LSI, and how to build websites that support LSI the right way (the Silo structure).
It is a bit heavy, but, boy, its packed with real information.
In addition the seo2020 website has tons of tutorials in finding keywords, and all sorts of things.
I think the publisher is more or less behind Zoomtracker, and does have a number of follow up products to the book, but as far as I can tell, they're not a "force-sell".
I haven't forked out $800/month to participate in Stompernet rollout (which I think is brilliantly done - the boys would be buying their yachts by now), but I am told that the information in this book is exactly the same as the Stompernet method.
Again, no affiliate links in this post, cuz I couldn't find one :-P
Markus