@noleli I think this isn't exactly what I'm looking for. I have a notes app (Obsidian) but I'm looking for something where the interface is optimized to just quickly store images or text that I'm *about* to do something with—but not quite quickly enough to just keep it in the clipboard. I suppose a clipboard history manager would also achieve this for me.

Someone has suggested to me "Stickies" which, against all reason, still exists and still looks more or less the way it did in System 7. Including an old pixel Mac icon!

Very uncharacteristic since Apple generally hates nostalgia as an aesthetic. I can only assume no one inside Apple has looked at this app in a decade.

@harris

It probably sounds silly, but you should take a close look at Stickies (doesn't take long). The most relevant aspect, in terms of what you're after is Optn-Cmd-F... to 'float' the window above all others. So as you switch between apps, it's omni-present. Also, if you use multiple Desktops, you can 'assign' Stickies to 'None' via the Dock and it will then 'stick' above everything, everywhere. Drag-in images from the Clipboard is useful too.