ISLISP contrib is a set of lisp libraries for the
"ISO/IEC 13816:1997(E) : Programming Language ISLISP",
the International Standard version of Lisp standardized by ISO in 1997.
CLISP is a portable ANSI Common Lisp implementation and development environment by Bruno Haible. Interpreter, compiler, debugger, CLOS, MOP, FFI, Unicode, sockets, CLX. UI in English, German, French, Spanish, Dutch, Russian, and Danish.
RSLisp is a new dialect of Lisp which works on the NET Framework with a special compilation/interpretation model. If you wish you can download the source and build it yourself for Linux (requires Mono Framework), but I don't promise that it'll work
ELCO stands for Embedded Lisp COmpiler or Esdens Lisp COmpiler. The goal is to create a lisp compiler for embedded 32bit architectures. (i.e. ARM) With this compiler you are able to write lisp code on a naked chip. No OS needed.