Here's a study on improving fluid intellience from Jaeggi and Buschkuehl (two of the people on their team): http://www.pnas.org/content/early/2008/04/25/0801268105.full...
Does anyone here have any experience actually using this?
For the skeptics, http://www.gwern.net/DNB%20FAQ#criticism
I highly recommend "Moonwalking With Einstein" by Joshua Foer about his experiences training alongside memory championship competitors. Also, working memory tends to be domain-specific and there's little transfer as you mention, see K. Anders Ericsson: http://www.psy.fsu.edu/faculty/ericsson/ericsson.exp.perf.ht...
Really enjoyed your post though, shooting you an email now...
At least it will definitely help you with short term memory and focus.