Once again, I'm not talking about who invented them. I'm talking about the innovations in tiling managers in Linux WMs. I somehow doubt you'll find something as good as AwesomeWM in pre-Linux WMs.
In AwesomeWM, you don't have workspaces, you have tags. Each tag can have its own window layout. A given window can have multiple tags. As an example, I can have my terminal on tag 1, Firefox on tag 2, Emacs on tag 3. The tags appear like your typical workspaces.
Then I consult Firefox and need to type a command into the terminal. I can quickly assign tag 4 to both Firefox and the terminal. When I click on tag ("workspace" 4), I have both FF and the terminal tiled. If I go back to tag 1, it's just the terminal - or tag 2 and it's just Firefox.
If you want to think in terms of workspaces, it's the equivalent of having your window in multiple workspaces.
But even better: Instead of assigning tags 4 to both of them, I can just say "Let's temporarily combine tags 1, 2 and 3", and I'll have a (transient) view with all 3 windows, tiled. Very handy if I just need to do it for a short period of time - no need to untag 4 from all of them.
This way you can quickly do the "union" and "difference" of different tags as needed - really quickly. Say I've got both FF and Emacs in one tag. Then I need to quickly run a terminal command and copy/paste the output. I just say "Hey, let's do a union with tag 1, run the command, and undo the union."
Once you get used to it, you miss it in any window manager that doesn't have it.
