The "Open On-Chip Debugger" provides JTAG/SWD access from GDB (or directly with TCL scripts) to processors with ARM and MIPS based cores.
See website for full list of supported targets.
BEYE (Binary EYE) is a free, portable, advanced file viewer with built-in editor for binary, hexadecimal and disassembler modes. It contains a highlight AVR/Java/i86-AMD64/ARM-XScale/PPC-64 and other disassembler, full preview of MZ,NE,PE,ELF and other.