My favorite 3d Modeling Program, Rhino3d, has a built in command line stemming from its Autocad heritage.
It is absolutely amazing, and has been for two decades now. Rhino3d is by far the best 3d modeling program I have ever used, and I'd say it is downright fun to use!
Auto-complete, discoverability, and the way it mixes keyboard and mouse input all come together to make this wonderful experience. A basic example, tell it to draw an ellipsoid, click the starting point, type the width in one dimension, and then click the mouse for the third point.
In comparison to Sketchup I am easily 5x-10x more productive in Rhino (not just because of the command line, lots of other reasons, Rhino3d really is awesome).
I wish more applications had built in command lines that mixed mouse and textual input so well together. IMHO the greatest contribution VS Code has made is bringing that sort of combined UI to the programming masses, and doing it really well.
Rhino3d was, AFAIK, one of the earlier re-imaginings of that paradigm. (The CAD world doesn't move too fast!)
Autocad has released slews of products since I last looked at any of this, but I still really enjoy using Rhino3d. It feels like a natural extension of my mind and body, it is that good to use.
I don't even have a reason to do 3d modeling anymore, and I'll still open it up sometimes just to do something in it.
Gah I can't believe Blender and Sketchup became popular with their WTF UIs. Or why they didn't just copy a good UI from the get go.
xterm -geometry 150x1+0+0 &
domterm html '<iframe src="https://example.com" width="100%" height="400">'
I think this is potentially more useful than embedding X applications since an application with an embedded http-server can conceptually do anything an X application can do but with a more portable (and remote-able) toolkit. (DomTerm itself is an application with an embedded http server.)
Unfortunately, the interfaces which need this treatment the most are the ones least likely to get it, since big companies (even those that do not intentionally profit by obscuring what they know about you from you) are terrified of what you might do with your own data if given anything more than laboriously point-and-click access to it.
(EDIT: Hi, PeopleSoft! I hate you!)
Hearkens back to another time...
xinit ./xinitrc -- /usr/bin/Xephyr :100 -screen 960x540 -dpi 96