Braille art
Text graphics built from Unicode's braille characters, where each character acts as a two-by-four pixel grid.
The Braille Patterns block (U+2800–U+28FF) contains all 256 combinations of an eight-dot braille cell. For anyone drawing in a terminal that is a gift: one character becomes a tiny bitmap with eight addressable dots, roughly eight times the resolution of an ordinary character in ASCII art. The Python library drawille (2014) popularised the trick, and system monitors and charting tools now draw their curves with it.
The catch is that the characters really are braille. A screen reader will read the picture aloud as a stream of meaningless dot patterns — a reminder that one person's aesthetic discovery can be someone else's accessibility problem.