Boehm Garbage Collector: http://www.hpl.hp.com/personal/Hans_Boehm/gc/
CSRI: ftp://ftp.cs.toronto.edu/pub/moraes/malloc.tar.gz
GNU Malloc: ftp://ftp.cs.colorado.edu/pub/misc/malloc-implementations/
Hoard: http://www.cs.utexas.edu/users/emery/hoard/
Ptmalloc (GNU C Library): http://www.malloc.de/en/index.html
QuickFit Malloc: ftp://ftp.cs.colorado.edu/pub/misc/qf.c
vmalloc (Part of ast): http://www.research.att.com/sw/download/