Thanks for the information! That does look pretty damning for dual n-back. As for creatine, I'm not vegetarian but my meat consumption is lower than average, especially when I'm not weight training. At any rate, I stopped taking it after a couple of months because I decided the unknown long-term health risk from increased renal stress wasn't worth it.
EDIT: I am canceling this contest because I feel that the structure of the incentives were poorly thought out (see gwern's comments). I will be posting a new better structured contest in the near future (now posted). If you feel this is unfair or otherwise feel slighted, please contact me at my username at gmail.com.
I'm interested in making projects happen on Less Wrong. In order to find out what works and to inspire others to try things too, I'm sponsoring the following small project:
I hereby offer a prize to the first person to submit a good summary of the evidence on Spaced Repetition to the main page. The winner will get the prize, currently: $265 + 40 to charity (see comments)
The summary should address at least the following questions: