If you didn't shudder in recognition, you probably aren't familiar with TVTropes.org. It is an extensive wiki that started as "Television Tropes and Idioms" and eventually sprawled into just about every storytelling medium. It is also an enormous timesink because there is so much of it to read and each link tempts one to click, if only to find out what the heck a "Big Lipped Alligator Moment" is. (In case you wondered, it's a scene that comes completely out of nowhere, has no bearing on the plot and is never spoken of again.)
Tropes are things like plot devices, characters or settings that are seen over and over in various iterations. Anybody who thinks they have the most amazingly original idea in the world can quickly be disabused of that notion with a trip to TVTropes.org, where they can find entries for just about every little thing that they thought unique about it--with a long list of examples from various media.
I've come across a number of tropes that apply to my work-in-progress. It's simultaneously enlightening and humbling. I'm a touch relieved that none of the tropes I've discovered in my work appear to be particularly threadbare ones (the term "Dead Horse Trope" is used for those) and some even seem to be popular in a way that suggests that there is indeed an audience for this work beyond myself.
I'm tempted to insert my own examples once the book is published, though that's probably cheating. I know I'll have definitely achieved my dream if a complete stranger reads my book and loves it enough to make sure it's properly indexed there.