The Modern world? If "Modern" means "Not ancient and still around", then hmm.
Okay, here's an off-the-cuff list, in no particular order:
3. The Constitution of the United States.
6. Rock and Roll.
7. The Internet.
8. Bonus: Cameras. Because I still can't figure out why they work except by MAGIC.
A list of Seven Wonders of the Natural World would have been so, SO much more interesting.