Examples of tropes include "The Power of Friendship", "Million to One Chance", and "Anti-Hero" - though some of them have odder names, such as "Dark Horse Casting" (a mostly unknown actor is cast for a prominent leading role), "Narm" (the TVTropes term for bathos), or "Applied Phlebotinum" (a gadget, material, physics rule, etc. that exists for the sole purpose of furthering the plot).
This results in what could be described as at least partially an Anti PatternLanguage - a way to identify writing pitfalls (see [1]). It can also be used to identify good patterns, but they had to write a "Tropes Are Not Bad" page because people were mistaking it for being solely for AntiPatterns.
It uses a custom WikiEngine that was once PmWiki but has since been extensively modified; their changes are not open-source.
Readers of this wiki may be interested in their Wiki Tropes category, which is not especially extensive but does have a few interesting observations about their internal culture and how wikis are seen in media: [2]