Lisp: Common Lisp, Racket, Clojure, Emacs Lisp
A “hyperpolyglot” (although technically only a quadglot) that is a side-by-side reference sheet for Common Lisp, Racket, Clojure, and, Emacs Lisp.
One of the Hexaglot versions of the Bible included: Old Testament in Hebrew, Greek, Latin, English, German and French; New Testament in Greek, Syriac, Latin, English, German and French.
For another interesting example of analog information retrieval, see: Complutensian Polyglot Bible
Note that the location of the parallel texts meant the reader did not lose their original context when consulting another text. Unlike hyperlinks that take a reader away from the current resource.
Just out of curiosity I backed up the URL and found: Hyperpolyglot.
Which includes side by side references for:
Programming Languages
commonly used features in a side-by-side format
Interpreted Languages: JavaScript, PHP, Python, Ruby More Interpreted Languages: Perl, Tcl, Lua, Groovy C++ Style Languages: C++, Objective-C, Java, C# Languages in the Key of C: C, Go Pascal Style Languages: Pascal, Ada, PL/pgSQL Lisp Dialects: Common Lisp, Racket, Clojure, Emacs Lisp ML Dialects and Friends: OCaml, F#, Scala, Haskell Prolog and Erlang: Prolog, Erlang Stack-Oriented Languages: Forth, PostScript, Factor Operating System Automation: POSIX Shell, AppleScript, PowerShell Relational Data Languages: SQL, Awk, Pig Numerical Analysis & Statistics: MATLAB, R, NumPy and Fortran Computer Algebra Software: Mathematica, SymPy, Pari/GP Programming Tools
Unix Shells: Bash, Fish, Ksh, Tcsh, Zsh Text Mode Editors: Vim, Emacs, Nano Version Control: Git, Mercurial Build Tools: Make, Rake, Ant Terminal Multiplexers: Screen, Tmux Databases: PostgreSQL, MySQL, SQLite, Redis, MongoDB, Neo4j Markup: Markdown, reStructuredText, MediaWiki, Wikidot, LaTeX 2D Vector Graphics: PostScript, Processing, SVG Mathematical Notation: LaTeX, Mathematica, HTML Entities, Unicode
Of course, one downside to such a listing is that it would be difficult to supplement the information given without manually editing the tables.