Neko

Kirby with headphones

Utility Zone

Free programs I think are interesting or handy. Also doubles as a reference for me. Please let me know of anything else I could add in the comments at the bottom.

A MegaCollection

Based on Windows OS

Find more at tinytools.directory.

File Types and Protocols

Programs

Terminal

Other Utilities

System Tray
MiniBin Recycle Bin management in the system tray
SuperF4 Shortcut to kill programs.
Sidebar Diagnostics Quick system information access.
CapsLock Indicator Self-explanatory.
Background
Unchecky Skips extra programs in installers.
MacType (Github) Renders system fonts like how Mac does.
Ludusavi Backup game saves. I use it as a Playnite extension.
Microsoft PowerToys Some handy utilities, such as the text extractor.
Link Shell Extension Create Linux-style symbolic links from the shell.
Syncthing SyncTrayzor (Github) Decentralized file synchronization.
ROM Properties Adds ROm files support to file browsers, from viewing properties to image previews.
Programs
Display Driver Uninstaller Useful when updating the graphics card.
Steam Cleaner Deletes leftover data from games.
BetterDiscord Adds themes and plugins, including tabs.
Remove Empty Directories (RED) Clean up empty folders.
SpeedyFox Database optimizer for browsers and email clients.
ANSIWAVE Modern BBS.

Firefox Extensions

Visual Studio Code Extensions

Code Spell Checker, HTML / XML / RSS link checker, HTML CSS Support, Live Preview, open in browser, Path Intellisense, PDF Preview, Prettier - Code formatter, VS Code Pets

Paid Programs

Interesting

I do not use these, but I think they're neat, so I'm shouting them out here.

WinCompose A compose key to write special characters.
AltSnap Fork of AltDrag that adds snapping to edges along with using Alt to move windows.
AutoHotkey Programmable keybinds.
WACUP (WinAmp Community Update Project) Patch Winamp.
PortableApps Portable app manager.
Decker (Itch.io) Basically a spiritual sequel to Mac's HyperCard.
Browsers
Browsh Modern text-based browser that can run in SSH.
Beaker Browser (Archived) Peer-to-peer Web browser.
Text Editors
Vim Advanced text editor.
Doom Emacs GNU Emacs framework.
For Videogames
ReShade Post-processing injector for games and video software.
Moonlight Open-source client for NVIDIA GameStream.
Sunshine Open-source self-hosted game stream host for Moonlight.
Universal Hint System Handy hints for adventure games and more.
File Sharing
Retroshare Peer-to-Peer network for file sharing and messaging.
Soulseek File sharing network.
Nicotine+ Alternative client for Soulseek.

Suggest more in the comments!