Useful to nobody: generate accurate Windows 3.x dither patterns for any colour in your browser. mwh.nz/dither/

And also an ongoing, esoteric prototype on the distance side: it's term-rewriting on multisets of terms, where clusters of adjacent grid cells make up a multiset, and distant groups are independent until they touch. It's very impractical but distance (gaps) are semantic: ecs.vuw.ac.nz/~mwh/anatile/