World culture, economics, business and politics will change in the next year in ways we can't imagine. Or can we? Several hundred readers have written in over the past couple of weeks to propose global investment themes that they believe will play out in the next 12 months. They believe these themes are barely visible to the casual observer, but ultimately will electrify our imagination and attract scads of capital. In no particular order, here are four reader-proposed themes that could have the most potential. Most are right out in the open; there are few secrets. Their power as investments pivots on whether you think they are already so well-known that they're played out, or whether you think they're only minor sideshows in the big circus of modern life.