Here's a fun adventure for a slightly gonzo campaign. There's a huge iron wheel rolling across the landscape. Get inside and divert the wheel before it crushes a city.
The Roving WheelThe dungeon's a real page-turner.
I'll get my coat.
It's released under CC-BY-NC, so feel free to hack, edit, remix, translate, or whatever else you'd like. Here's a blank wheel image if you don't want to make your own.