In Eclipse, I can switch worskpaces by going to File > Switch Workspace ... but it doesn't give any indication of which workspace I have open at the time.... until now!

The -showLocation parameter causes Eclipse to show the current workspace name in the title bar of the application window (as well as the perspective name for the open perspective).

To add this to your Eclipse configuration (in Windows) is very easy:
Just right-click the shortcut you use to open Eclipse, and select 'properties'.
Then, add "-showLocation" (without the quotes) to the end of the "Target" line.

My shortcut target was: C:\ECLIPSE35\eclipse\eclipse.exe 3.5
Now it looks like this: C:\ECLIPSE35\eclipse\eclipse.exe 3.5 -showLocation