DbgKit is the first GUI extension for Debugging Tools for Windows (WinDbg, KD, CDB, NTSD).
OneDbg is a handy tool that provides an easy way to debug multiple dump files.
PE Internals provides an easy way to view and modify the structure of executable (PE32 and PE32+) and object (COFF) files.
Symbols Explorer displays structures, unions, enums, global variables and functions names from pdb files.
Find is a tool to search for ansi, unicode and hexadecimal strings.