Apple - Can I show the Mission Control desktop number in the menu bar?
Maybe the open source WhichSpace project can do this:
WhichSpace
Have you ever forgotten which space is currently active on OS X (10.11+) and wanted a quick way to tell? Didn't think so... but I did!
Screenshot
I could not find any built-in feature for this, so I decided to use the backgrounds.
I found a background image that I wanted, and made 8 copies of it.
Then I wrote the numbers 1-8 on each of them, next to where the dock usually is.
Then you press ctrl+1 to make sure you're in desktop 1, right click the background, and choose the image with 1 written on it.
Then close down the system preference box (otherwise you end up changing only desktop one).
Then press ctrl+2 and do right click again.
Not allowed to post screenshot :( to show how it looks.
This problem now has a much more robust solution, thanks to Total Spaces. This app brings back the old 2D grid of spaces and shows the space number in the menu bar.