https://www.youtube.com/watch?v=LBfUVIhFaLc
https://www.youtube.com/watch?v=PxLNIvuHj00
This is a feature I've been thinking about for a bit now, and there are certainly other Minetest users who agree it would be awesome to have. There are many engines that support interactive surfaces: The best example is Doom 3 (idTech 4), famed for having screens around the map that players can manipulate and click buttons on. Then there's Second Life, which supports interactive web pages on surfaces which you can click / scroll / etc like in any browser.
What I'm trying to suggest for Minetest is a simpler implementation: Formspecs on surfaces. First of all, I'm wondering whether it's possible to dynamically generate a texture from a formspec, which can be applied to any drawtype or surface. And second, if we can detect where the player's crosshair is pointing on that texture, so buttons and input fields can be clicked on and selected.
What purpose would it serve? Well doh... realistic terminals of course! We could create node definitions for screens, containing formspecs that operate nearby devices or have other effects on the surrounding world (calling Technic mod here). One idea: Keypads that open locked doors when you introduce the right combination. Obviously we can already do this... just that the formspec floats in front of the player who clicks the screen, whereas with this ability it would appear on the actual surface and work as an in-game touchscreen.
Here's a crude mockup of how what I'm imagining would look like: