So here is a list of random ideas from Dark Sun, Mad Max, Dune, Fallout, and a bunch of different stuff. 1-10 are places, 11-20 are related to transportation, 21-30 are factions, 31-40 are visuals and apparel, 40-45 are dangers, and 46-50 objects.
Or, to sum up some ideas in the proverbial 25 words or less (almost):
Maniacs, mutants, and marauders, carrying obsidian and bone, ride oil-eating dragons through Endless Sands. Psionic monks battle radioactive sorcerers, dinosaurs and warlords in the apocalyptic heat.
2. Endless “seas” of silt, salt, or glass (excessive Ss, sorry).
3. Sky-high monasteries where holy-people sharpen their martial skills.
4. Underground vaults with the last surviving fragments of the Old World.
5. A building with innumerable floors inside the tableland.
6. A hill labyrinth of colored sands.
7. The Vermilion plains, where even the trees have red leaves.
8. The moving metropolis.
9. The green places, filed with cannibals and dangerous animals.
10. Cursed pyramids, with the remains of alien humanoids. . . and their destroyers.
11. Petrol-eating, fire-spitting, many-legged drakes that run around like crazy after a good meal.
12. Velociraptors, tyrannosaurs, stampeding apatosaurs and, why not, pterosaurs.
13. Flying ships and stingrays.
14. Sandworms, purple-worms, or bulletes.
15. Giant insects.
16. Tree-hoping people.
17. Relentless runners.
18. Gigantic warmachines.
19. Psionic teleportation.
20. Caravans, controlled by merchant-princes.
21. Bloodthirsty youngsters eager to die in epic ways.
22. The genetically engineered, with perfect bodies and deranged minds.
23. Scorpion-smoking religious assassins.
24. Preservers of the last seeds.
25. Mutant sand raiders.
26. Psionic monks.
27. Rabid cannibals.
28. Woman-hating slavers. . .
29. . . . and the Amazons who survive them.
30. The great desperate mass.
31. Leather, piercings and unusual hairstyles.
32. Shaved heads, black and white paint, faces like skulls.
33. S&M apparel.
34. Demon masks and bizarre armor.
35. Half naked with sunburns and unkempt hair.
36. Heavy brown robes, kerchiefs and goggles.
37. Silk robes with vivid colors.
38. Ritual scarification.
39. Bones and human ashes as accessories.
41. Sandstorms and lightning.
42. No ozone layer, sunlight slowly kills you.
43. Water is scarce, non-radioactive water is scarcer.
44. Sinkholes and the things that cause them.
45. Desert monsters above and below the ground.
46. Flowers as signs of extreme wealth.
47. A spice that causes hallucinations, mutations and increases psychic abilities.
48. Weapons made of obsidian, glass and bone.
49. Spikes in armors, mounts and buildings.