http://www.livescience.com/36143-iq-change-time.html
Khan Academy is a good place to start, but has the problem of very little feedback.
You could try to pick up programming, which more or less is just solving logic puzzles.
More important than IQ is tenacity. Many high IQ people give up and quit programming because it takes a long time to 'get'. So who cares if a brilliant physicist with 150 iQ can become a competent programmer or mathematician in two years and it takes you three and a half years. (answer: nobody).