ONTD comunities are based on the most popular Livejournal community - Oh No They Didn't - also known as ONTD - a pop culture gossip site whose slogan is "The celebrities are disposable. The content is priceless."
Spin off communtities specific to particular fandoms have arisen over the last two years. They reproduce the key cultural elements of ONTD - snark, the posting of macros and animated .gifs, and the invention of vernacular specific to that community.
The two most popular fandom spinoff comms are American Idol and Star Trek, which have become key shapers of the culture of those fandoms on Livejournal. The profile of ONTD comms in supernatural fandom is less prominent.