Jettison is great for ejecting and optionally remounting external disks when you put the Mac in and out of sleep.
Turbo Boost Switcher is useful for getting the Mac to run cooler and prolong battery life. Mine is nearly always plugged in at my office, so I use it when I don't want the fan to get loud (like when recording with a microphone).
I'm not sure if BetterTouchTool qualifies as "less known", but it's really useful. I use it to launch new iTerm windows and various apps on the f16..f19 keys on the Magic Keyboard. I also use it to extend other applications with macros. It would be great if Obsidian had Emmet-like facilities to expand abbreviations, so you can set up BetterTouchTool to expand expressions like "h4" followed by the tab key into "####". Things like that really speed up markdown entry.
https://stclairsoft.com/Jettison/