YaraEditor is a tool that will help you to write and test signatures for the Yara engine. To learn how to write signatures with the Yara syntax, please refer to the proper documentation.
Adlice PEViewer (RogueKillerPE) is a PE parsing tool, able to show internal structure of executable files. It's able to read either the memory image (process module) or the disk image (filesystem) of a given executable.
LogAnalyzer is a program able to analyse reports generated by many diagnostic tools (HijackThis, ZHPDiag, OTL, ...)
MD5Look is a program able to search for a given MD5 hash across the child folders of a given root.
DiffView is a program able to display and log modifications made by a program on the system, in the filesystem and the registry.
TaskSTRun is a process explorer able to display system information about autostart entries, running process, services, tasks, and network events.