This is absolutely my favourite site of the moment.  For real.  I have spent hours, with which I could have done a lot better things, reading it and laughing quite often at the descriptions within.

To quote from the main page:

Tropes are devices and conventions that a writer can reasonably rely on as being present in the audience members’ minds and expectations. On the whole, tropes are not clichés. The word clichéd means “stereotyped and trite”. In other words, dull and uninteresting. We are not looking for dull and uninteresting entries. We are here to recognize tropes and play with them, not to make fun of them.

The wiki is called “TV Tropes” because that is where we started. Over the course of a few years, our scope has crept out to include other media. Tropes transcend television. They exist in life, as we will be quick to tell you. Since a lot of art, especially the popular arts, does its best to reflect life, tropes are likely to show up everywhere. We want ’em all.

As someone who enjoys writing myself, a site like this is incredibly useful.  But even for the casual reader or watcher of television, its a really great site and I cannot recommend it enough.  If you want to visit, please follow the link.