Here’s a fun one. According to its author, John Koenig:

The Dictionary of Obscure Sorrows is a compendium of invented words written by John Koenig. Each original definition aims to fill a hole in the language—to give a name to emotions we all might experience but don’t yet have a word for.

Great idea, and the entries are even better. An example:

onism
n. the frustration of being stuck in just one body, that inhabits only one place at a time, which is like standing in front of the departures screen at an airport, flickering over with strange place names like other people’s passwords, each representing one more thing you’ll never get to see before you die—and all because, as the arrow on the map helpfully points out, you are here.