I just selected the "Intend to Buy" option for Metroid Other M and completed the survey, but the "Product Registration" didn't appear in the to-do list like the other games. I noticed that I had three Intend to Buys waiting, and I had heard a rumour that three is the most you can have at one time. It would appear that could be true.
Unfortunately, one of the Intend to Buy games is Dragon Quest IX, which I do not remember selecting. I'm not sure why I would've done that... I knew my friend was going to buy the game, but she has a Club Nintendo account too, so I wouldn't get a code from her. Hmm...