What's better than a good idea? Two good ideas in one blog post! Both have to do with concrete or asphalt, so I thought they'd go together.
1.) Even when I mentioned the long-lasting glow-in-the-dark pebbles for driveways earlier, I didn't think of this use for them: embed them in roads for glowing directional signals, even without streetlights. They can even be made temperature sensitive, so when the road gets icy, big glowing snowflakes could appear on it. This is a great idea (although implementing it could run into some problems in Seattle given our infamous lack of sun in the winter months).
2.) Instead of glowing pebbles, mix in something much smaller into concrete: bacteria. Bacterial spores can survive a long time without water or nutrients. When the concrete is cracked, the water will wake them up (like Sea Monkeys) and they'll start making carbonate. Deposits of calcium will react with this to make calcium carbonate (calcite) which is a little bit of mortar that will fill in the crack. The result is self-healing concrete.
The problem is keeping the bacteria alive in the concrete for a long enough time, but they're working on that. Given how long some spores can survive, this might just work.
Realize that this shows that you can use bacterial spores as dormant little chemists waiting to control their environment through chemistry: in this case, ejecting carbonate and making concrete in a newly formed crack. Life is a powerful thing, if you can keep it alive in the place where you want it to work.