Boomerang is a decompiler that takes executable files and attempts to create a high level, compilable, possibly even maintainable source file that does the same thing. It does not matter if the executable file has symbols or not, or whether it was compiled using any particular language.
Linux Debug is a functional clone of the old DOS debug.com for x86 linux. Functions include the ability to alter/examine memory and registers, set/clear breakpoints, step into and trace over, symmetric symbolic disassembler, and symbolic assembler. It has a simplified UI, and can work with bin and elf format files. Symbolic functions work only if debug symbols available in the file header. It features a NASM-compatible syntax for both disassembler and single line assembler.
Hachoir is a Python library used to represent a binary file as a tree of Python objects. Each object has a type, a value, an address, etc. The goal is to be able to know the meaning of each bit in a file. Hachoir is able to open invalid or truncated files. It only reads or computes data on demand to minimize load times. Many field types are predefined (integer, bit, string, etc.) and strings with a given character set (such as ISO-8859-1 or UTF-8) are supported. Addresses and sizes are stored in bits.
vAVRdisasm is an Atmel 8-bit AVR firmware disassembler. This single-pass disassembler can read Atmel Generic, Intel HEX8, and Motorola S-Record formatted binary files containing valid AVR firmware. vAVRdisasm is capable of a variety of formatting options, and can output directly assemble-able code.