TV Tropes Will Ruin Your Life - Television Tropes & Idioms. Actually, it covers all forms of narrative, and it's essential reading for anyone who writes. Think you've just come up with a great new twist? Check it here first.
The Periodic Table of Storytelling - All these tropes and twenty thousand more are detailed on http://tvtropes.org/pmwiki/pmwiki.php/Main/HomePage (Tropes are devices and conventions that a writer can reasonably rely on as being present in the audience members' minds and expectations.)