I like the Chemical Luminescence Keychain idea. Pollution is getting worse and worse and some kids are even developing asthma from the low quality of their air. This would be extremely useful especially if you were going to an area you were unfamiliar with.
I wish the kid uber idea was more wide spread. I love the idea of parents being able to trust someone to get their child some place they need to be when they are not available to do it themselves. From your 2X2s I can see that there are some services out there like this but they are limited to some areas.
What if there were more options for wearable smoke detectors? Who do you think would start buying these items first? Would they start off as bracelets and necklaces and then eventually become something you could wear?