A disassembler -- or, more appropriately, a disassembly environment.
The idea is that you have an interpreter, much as you would in Perl
or Python, which allows you to load files, disassemble them, dump
the disassembly, write/run macros, and various other operations. The
x86 instruction disassembler written for this project has been packaged
separately as libdisasm, and is intended to be used in other open source
projects.