A list of all of the interrupts in the 32-bit x86 CPU architecture.
A disassembler for Windows. One of the best in the field, and v2.0 just went beta. It's shareware, though it doesn't appear to lack any functionality if you haven't purchased it yet.
An open source modular macro assembler that supports a number of CPU architectures out of the box and makes it easy to add new ones.