WinLaunch
https://sourceforge.net/projects/winlaunch/
-- launchpad for Windows, throw mouse to top left to access. Supports multiple pages. Good way to keep the Desktop clean as well as a way to quickly launch stuff.
HashTab
http://implbits.com/products/hashtab/
-- Easy file hashing tool, adds a tab "File Hashes" to file properties dialog, to which you can drag another file to compare hashes. By default displays and compares CRC-32, MD5, SHA-1 but supports a total of 30 different hashing methods (right-click the hash type section and click Settings)
Everything
https://www.voidtools.com/
-- Instant file search tool. By the time you finish typing, the results are in. A must-have. Supports keyboard shortcuts to quickly launch a new search window.
Folding@Home
https://foldingathome.org/start-folding/
-- Allows your computer's CPU and GPU, when you're not using it, to
form Voltron form a super-computer with others and tackle medical problems (such as Alzheimer's, Huntington's, Parkinson's, Cancer, and recently, COVID-19). Be sure to select whether is should fold while you work or only when idle. You can easily use your computer normally (as long as it's got nominal specs and it's slow) with it running, but if you're gaming or otherwise using a lot of your computer's potential, you should select to fold when idle or you might get a bit of a performance hit.
ShareX
https://getsharex.com/
-- Easily copy parts of your screen, active window, etc etc, and export to a multitude of destinations (including just a local file, of course). Supports keyboard shortcuts. Excellent little tool, check it out.
Lightshot
https://app.prntscr.com/en/index.html
-- Like ShareX, maybe a few less destinations supported, but also supports Mac.
PlayNite
https://playnite.link/
-- Universal Game Launcher. Supports almost all Game Stores (Steam, Epic Games, GOG, Origin, Humble Bundle, itch.io, Uplay / Ubisoft, Battle.net, MS / Xbox, and custom emulators. Downloads game metadata from the net so you have all the box art & info. Really nice. Regularly updated.
DBGL / DOSBox Game Launcher
http://members.quicknet.nl/blankendaalr/dbgl/
-- Frontend for DOSBox, makes it very easy to configure DOSBox and game for DOSBox, with downloadable profiles for games etc.
PortableApps
https://portableapps.com/
-- Get the Platform, for a central location to install, update, and launch PortableApps, or download individual Apps from the site for standalone use. Useful for keeping a bunch of tools / programs on a removable device for use with other computers without downloading / installing them, or just maintaining a your own tools / programs that don't have to be installed and survive Windows re-installs with all your settings intact (as long as the drive where it's located isn't wiped and you don't put it in \Program Files or \Windows, that is). A
shocking number of the apps already listed here in this thread are available on PortableApps.
SuperF4
https://stefansundin.github.io/superf4/
-- Ability to force-close programs that refuse to close by normal Task Manager means, as well as point and click at what you want closed if you don't know the task name.
FastCopy
https://fastcopy.jp/en/
-- One of the best if not the best file copy utilities. Useful for saving time with large data transfers, as well as managing to recover what data is possible from damaged storage. Supports context menu (right-click) use, so you can keep it as an option but use normal copy / paste for everyday stuff if you want.
WinMerge
https://winmerge.org/
-- Easily compare text files side-by-side with differences highlighted and merge what changes you want. Also supports comparing file directories.
86Box
https://ci.86box.net/job/86Box-Optimized/
https://github.com/86Box/roms/releases
https://github.com/86Box/86BoxManager
https://winworldpc.com/library/operating-systems
-- PCem fork (updated more often with more features). Emulates an entire legacy machine, letting you choose individual models of Motherboard / BIOS, CPU, memory, Sound Card, Video Card, Network Card, storage devices, and more. Very handy. You'll need 86Box optimized for your specific CPU (1st link), the ROMs of the different devices supported (2nd link), and the frontend / manager (3rd link), and of course an OS to put on your new machine(s) (4th link). Updated often with more device support and fixes, so check back often.
HxD
https://mh-nexus.de/en/hxd/
-- Hex editor.
SysInternals / NirSoft / Roadkil / Rayer
https://docs.microsoft.com/en-us/sysinternals/
https://www.nirsoft.net/
https://www.roadkil.net/index.php
http://rayer.g6.cz/programm/programe.htm
-- Massive lists of useful utilities and tools. Some rather advanced ones too. Like Swiss Army Knives for your computer. Throw 'em on a drive and update them once in a while.