High Level Assembler and Toolkit (HLASM)

System/390 assembler toolkit for MVS & VM & VSE (HLASM) including disassembler, by IBM.
http://www-3.ibm.com/software/awdtools/hlasm/

TRACE32

Microprocessor Development Tools include multi processor emulators and disassemblers.
http://www.lauterbach.com/

The dcc Decompiler

It decompiles small .exe files from the (i286, DOS) platform to C programs.
http://www.itee.uq.edu.au/~cristina/dcc.html

MacNosy

Is a Mac application that disassembles the Macintosh ROM or any 68K or PowerPC codes, by Jasik Designs.
http://www.jasik.com/nosy.html

IDA Pro

The multi-processor, multi-OS, interactive disassembler, by DataRescue.
http://www.datarescue.com/

Universal Cross Disassembler

XDASM - DOS based cross-disassembler supports numerous processor types, by Data Sync Engineering.
http://www.datasynceng.com/xdasmdoc.htm

This96

80196 disassembler by zartoven.
http://www.winsite.com/bin/Info?500000032198

palmdeMON

A win32-based disassembler and resource viewer for Palm Pilot applications. Links to other Palm tools.
http://palmdemon.schwump.net/

Misosys Disassembler

Tim Mann's TRS-80 Page includes Misosys Disassembler, aka PRO-DUCE.
http://www.tim-mann.org/trs80.html

DASM1600

An Intellivision Disassembler by Frank Palazzolo.
http://www.dsplib.com/intv/dasm1600.html

the bastard disassembler

*NIX disassembler. Written in C on Linux for x86 ELF files; intended to support multiple CPUs, OSes, and file formats. Scriptable.
http://bastard.sourceforge.net/

DISA

An OS/2 disassembler for OS/2 device drivers, by Abbotsbury Software.
http://www.wdi.co.uk/abbsoft/aslprod.html

Application-specific Decompilers

Catalog of decompilers.
http://www.itee.uq.edu.au/~csmweb/decompilation/application.html

MELPS7700 Disassembler

By H.Kashima.
http://lillith.sk.tsukuba.ac.jp/~kashima/software/melps7700e.html

SST Global-Decompilers

Decompilers for IBM midrange systems.
http://www.sstglobal.com/

DSP5600x

A 5600x disassembler by Miloslaw Smyk.
http://wfmh.org.pl/projects/delfina/

AVATAR

A disassembler/patcher/code-explorer for PA-RISC based HP-UX systems, by Allegro Consultants, Inc.
http://www.allegro.com/products/hp9000/avatar.hpux.info.html

Re39

Interactive Disassembler for Rockwell C29/C39 (C40) code by Lewin A.R.W. Edwards.
http://www.zws.com/products/re39/index.html

Transputer disassembler.

By Andy Rabagliati.
http://www.wizzy.com/wizzy/dasm.html

SSEM

The World's First Stored Program Computer - disassembler included.
http://www.blueangel.demon.co.uk/ssem/ssem.html

FARGDIS

Fargo Disassembler for TI-92 DOS versioin, by John Grafton.
http://www.ticalc.org/archives/files/fileinfo/4/452.html

Reverse Engineering Compiler

Program that tries to make source coden (C) from binary, multiplatform. There are MIPS disassembler too, by Giampiero Caprino.
http://www.backerstreet.com/rec/rec.htm

PICE/WIN

Panasonic MN1500 Emulator Interface for Windows includes Disassembler for MN1500 by TransferTech.
http://fuzzy.cs.uni-magdeburg.de/afn/fofo97/ttech/pice_e.htm

The Decompilation Page

Decompilers, resources, and history.
http://catamaran.labs.cs.uu.nl/twiki/pt/bin/view/Transform/DeCompilation

Open Reverse Code Engineering

An open community site offering a number of services including blogs, forums, download and reference libraries.
http://www.openrce.org