2Bit is an online shrine to 2-bit graphics (i.e. four colors) with the focus on those produced by (or according to the hardware specifications of) the 1989 Nintendo Gameboy.
Of course graphics capabilities have evolved to display 16 million different colors. However, it has always amazed me that images of familiar things can still be recognized even if they are limited to just four colors, or even the absolute minimum of two! Probably the most important reason for my interest in 2-bit graphics can be said in one word: Gameboy. The original Gameboy was my first videogame system. It's what I grew up with. I have always liked the aesthetics about them and I still do to this day.
It's not all monochrome, but 2-bit color pallettes tended to be ugly because of the CGA standard. More subtle 2-bit pallettes were found on the Amstrad CPC and MSX. The ZX Spectrum is sometimes mistaken as a 2-bit deal, but it was in fact 3-bit with peculiar limitations.