EasyHook - The reinvention of Windows API Hooking
Deviare API Hook - Deviare is a professional open source hooking engine for instrumenting arbitrary Win32 functions, COM objects, and functions which symbols are located in program databases (PDBs).
Microsoft Research Detours - Detours is a software package for re-routing Win32 APIs underneath applications.
Insomnia REST - The most intuitive cross-platform REST API Client ð´
HookInjEx - How to inject code into another processes address space, and then execute it in the context of this process.
RESTer - A REST client for almost any web service (Firefox and Chrome extension).