A Perl 6 compiler written in Perl 6 itself, started by Mitchell Charity.
(well, the elf mostly-compatible-subset of p6). elf_h in http://svn.pugscode.org/pugs/misc/elf/ is a stand-alone p5 program, namely elf compiled to p5. the elfish/on_sbcl just swaps out the emitter. so elf_on_p5 can compile to p5 and to cl (depending on the emitter used), and so can elf_on_sbcl.