All you have to do is register your copy of Big Brain Academy: Wii Degree and fill out a quick online survey.
Nintendo of America has been slipping those "Register your Software" codes into their first party games for a few years now, but the people who do so have not been rewarded with much. There have been nowhere near as many free goodies offered in North America as there have been in Japan.
Well the customer service site just threw us a bone with this offer.
Nintendo wants to get to know our fans better through a special Big Brain Academy survey program. All you need to do is register your copy of Big Brain Academy: Wii Degree, and fill out a quick survey to get a free Wii Remote keychain. Click here to find out more!
This keychain is most likely the same light up keychain that was given to the press at the recent event held in Seattle.
Thanks to UncleBob in the forums for the heads up.