creatine supplementation increased the average IQ of their sample of vegetarians by 12 points
Creatine didn't improve my iq, but it did improve my scores on a digit memory test and more importantly, my mental stamina. I took it for a year, decided it wasn't doing anything and quit. After about a week, I noticed that I was feeling tired after six or seven hours of programming instead of the eight or nine I had been doing. After taking creatine again my energy returned.
Anecdotal blah blah, but maybe you should try it? It doesn't cost that much for a month's supply, and you can find simple recall tests online and do one measurement before and one after.