Spies and Monitors
This page covers third party tools for monitoring.
Process Explorer: show opened handles and loaded dll's 
Free tool to show which handles are opened or which dll's are loaded for the current running processes.
It offers also views for memory usage and CPU utilisation.
You can find info and download link here :
Process Explorer website
Process Monitor: show file (IO), registry and process/thread activity
Free tool to show activity of process file access, disc IO, access to registry and process activity.
It combines the features of legacy tools Regmon and Filemon.
You can find info and download link here :
Process Monitor website
Winspector: show window messages and hierarchies
Free tool to show messages on windows and the window hierarchy of running processes.
Resembles the good old Spy++ tool, but offers more features.
You can find info and download link here :
Winspector website
Portmon: monitor and display serial and parallel port activity
Free tool to show activity on serial and parallel ports of a system.
You can find info and download link here :
Portmon website
Dependency Walker: builds a hierarchical tree diagram of all dependent modules (dll, exe, ocx etc)
Dependency Walker is a free utility that scans any 32-bit or 64-bit Windows module (exe, dll, ocx, sys, etc.) and builds a hierarchical tree diagram of all dependent modules.
For each module found, it lists all the functions that are exported by that module, and which of those functions are actually being called by other modules.
Another view displays the minimum set of required files, along with detailed information about each file including a full path to the file, base address, version numbers, machine type, debug information, and more.
You can find info and download link here :
Dependency Walker website
GDIView: displays the list of GDI handles (brushes, pens, fonts, bitmaps, and others) opened by every process
It displays the total count for each type of GDI handle, as well as detailed information about each handle.
Nice feature is to display changes only (delta's) which helps in quickly finding leaks.
This tool can be useful for developers that need to trace GDI resources leak in their software
You can find info and download link here :
GDIView
