A trope is a convention, sometimes a cliché, that may be used as a formula for a specific purpose in a story. The quest, foreshadowing, or the faithful sidekick could be considered tropes for their implementation within a story. James R. Harris has given us a periodic table of the information found on TVtroupes.org, weighting each item in kilowicks (thousands of links to the relevant page on the site). To give you a taste of this potential guard against clichés in your own stories, here are items organized under “Setting, laws, plots” with their popularity rating:

• An Aesop 3.0
• Serious Business 4.0
• The Masquerade 1.7
• Recycled IN SPACE 3.2
• X Meets Y 2.3
• Magic A Is Magic A 0.75
• Sliding Scale of Idealism vs. Cynicism 1.6
• Status Quo Is God 2.0
• Call To Adventure 0.43
• Redemption Quest 0.20
• The Hero’s Journey 0.28
• Saving the World 0.38
• They Fight Crime .58

Of course, I picked the tame category. The plot device category has fun things like “Applied Phlebotinum“, an object or substance used to advance the plot. Here’s a good bit of dialogue as an example:

Nick Naylor: Cigarettes in space?

Jeff Megall: It’s the final frontier, Nick.

Nick Naylor: But wouldn’t they blow up in an all-oxygen environment?

Jeff Megall: (beat) Probably. But, you know, it’s an easy fix. One line of dialogue: ‘Thank God we created the, you know, whatever device.‘

— Thank You For Smoking

(via Fast CoDesign)