Suggestions for Letter-plain

The following packages have something in common with the package Letter-plain. The packages are ordered in decreasing similarity.

Package lettermac: Simple macros for writing letters (Plain TeX)
Package letter1: Letter formatting macros
Package automagic: Automatic counter numbering in Plain TeX
Package bellmac: Outline scheme for form letter production
Package figplace: Floating figures in Plain TeX
Package label-pln: Print address labels in three columns
Package twoside: Two-side typesetting in Plain TeX
Package toc-zar: Plain TeX table of contents macros
Package twocolumns: Knuth’s two-column output macros
Package list: Verbatim listing of text files
Package harvmac: Macros for scientific articles
Package resumemac: Plain TeX macros for resumés
Package mlawriter: Write MLA style documents in Plain TeX
Package histyle: A HighStyle environment for TeX
Package lextex: Typesetting legal documents using plain TeX
Package plain-widow: Three output routines that extend \plainoutput
Package plain-grid: Four sets of macros for typesetting on a baseline grid
Package laps: Zero-width boxes for annotations, etc.
Package ifis-macros: Check if a given input string is a number or dimension for TeX
Package toc: Table of contents macros for Plain TeX
Package font-selection: Font selection for plain TeX
Package font-change: Macros to change text and mathematics fonts in plain TeX
Package hyplain: Basic support for multiple languages in Plain TeX
Package fontch: Changing fonts, sizes and encodings in Plain TeX
Package pdcmac: Damian Cugley’s document tools
Package make-env: Print USPS standard envelopes
Package knuth-letter: Knuth’s example letter macros
Package eplain: Extended plain TeX macros
Package beletter: Typeset Belgian letters
Package shsulet: A letter document style for use at SHSU
Package graphics-pln: LaTeX-style graphics for Plain TeX users