Hi there,
I'm still trying to implement mental rotations (done) and semantics
into n-back, and I found some pretty interesting webpages along the
way. Like Cyc project (biggest hierarchical, common knowledge
database, supports inference, and has interesting ontology,
approximate example: "skin" is defined as 30% of "sheet" concept, 20%
of "body" concept, 20% surface and 10% covering..).
But two games I found are really fun AND interesting because of their
underlying semantics: first one is called Verbosity, and through
playing it you are actually feeding one database similar to Cyc:
http://www.gwap.com/gwap/gamesPreview/verbosity
Second one is really amazing. It guesses persons you think of, and I
guess, nobody and no software can beat it. Give it a few tries, start
with somebody popular, and then try to find somebody it WONT guess. It
once even said "YOU" - and it was right! ;)
http://en.akinator.com/