All reasonably stable tools
AccessMask - decode access mask for common object types
BgInfo - WPF version of the Sysinternals BgInfo tool
BITSMgr - BITS jobs manager application
CLR Explorer - View .NET process information / dump file
CpuStres - thread/CPU stress testing app
CpuStress v3 - thread/CPU stress testing app
DebugPrint - monitor OutputDebugString/DbgPrint(Ex) calls (no driver needed)
DriverMon - monitor any driver activity
ErrorLookup - error code description for Win32 (GetLastError) and NTSTATUS
ETWExplorer - view ETW XML manifests for registered providers
FSClass - lists the file system filter classes (command line)
GFlagsX - enhanced version of the GFlags tool
INF Studio - view/edit INF files
Kdump64 - generate a local kernel dump (64 bit)
KernelObjectView - View stats of kernel objects and handles in the system
MetroManager - list (and launch) installed Windows Runtime components and apps
MemMapView - view any process memory (including protected and minimal processes)
NtfsStreams - show NTFS alternate streams in files
ObjDir - command line tool to show object manager namespace
ObjExp - Object Explorer, explore objects and handles
PEExplorer - PE file viewer
PEExplorerV2 - PE file viewer version 2.0
PoolMonXv2 - kernel pool memory (version 2)
PdbView - view PDB files
PerfMonX - enhanced Performance Monitor tool
ProcMonX - ProcMon-like tool based on Event Tracing for Windows (ETW)
ProcMonX v2 - Enhanced ProcMon-like tool based on Event Tracing for Windows (ETW)
QSlice - modern version of the classic QSlice tool
QSliceX - pie chart graphics for QSlice
Sysrun - run any executable with the SYSTEM account (no service needed)
System Explorer - system, processes, threads, objects, handles, and other information - all in one tool
Total PE - Yet another PE viewer (WIP)
TotalReg - Total Registry - view/edit real Registry, undo/redo, and much more.
WindowTitleEx - Show HWND, TID, PID on windows. Revert with included tray icon
WinSpy - show windows and monitor messages. A WIP alternative to Spy++.
winsta - Show current session's window stations, desktops and top level visible windows (with non-empty titles)
WFP Explorer - Windows Filtering Platform Explorer
XCalculator (XCalc) - simple calculator supporting variables and functions