AVATAR - A disassembler/patcher/code-explorer for PA-RISC based HP-UX systems, by Allegro Consultants, Inc.
the bastard disassembler - *NIX disassembler. Written in C on Linux for x86 ELF files; intended to support multiple CPUs, OSes, and file formats. Scriptable.
The dcc Decompiler - It decompiles small .exe files from the (i286, DOS) platform to C programs.
Misosys Disassembler - Tim Mann's TRS-80 Page includes Misosys Disassembler, aka PRO-DUCE.
Open Reverse Code Engineering - An open community site offering a number of services including blogs, forums, download and reference libraries.
Re39 - Interactive Disassembler for Rockwell C29/C39 (C40) code by Lewin A.R.W. Edwards.
Reverse Engineering Compiler - Program that tries to make source coden (C) from binary, multiplatform. There are MIPS disassembler too, by Giampiero Caprino.