YTMND is not alone. There are many parallel dimensions to ours; many alternate universes.
The first alternate universe was PTKFGS, which stood for "Punch the Keys, for God's Sake!" This line was uttered by Sean Connery in Finding Forrester moments before the infamous "You're the man now, dog!" quote. Soon, sites were created that claimed to be sites from PTKFGS; in essence, implying that the ptkfgs.com website would have still been popular and successful but would offer idiosyncratic differences, becoming a bizarro YTMND.
One of the aspects that PTKFGS sites had in common was a different watermark; instead of the YTMND watermark in the top left corner, the PTKFGS watermark was located in the top right. YTMND users realized that there were still two corners left over.
The lower right corner was soon taken by YesYes, the universe based on another line from the same Finding Forrester scene. This universe was used to create sites that were alternate versions of both YTMND and PTKFGS fads.
After the discovery of YESYES, a debate rose up in the YTMND community about what the universe that takes the lower left corner should be. Complicating this fact is the lack of good lines from the original Finding Forrester scene; while Xenu blew it up. So yeah.and take their audio from the same scene, takes a line from a different scene, spoken by a different character, and takes a Connery line from a different move (specifically, Highlander). Eventually, an investigation took place, and it was discovered that the fouth corner was actually a . Caused when
Besides the main three universes and the multiple fourth universes, there are many other universes that have their own watermark. GAYTMND uses the first corner; KHANTMND uses the third corner, but the watermark is often rotated to fit in other corners.
Several fads take the name 'XTMND', where 'X' is whatever the fad is about; since these sites don't have a watermark, they are not considered separate universes. One of the most famous of these is 300TMND.