You can customize the window titles, either manually or automatically. The window title is normally associated with each tab and updates to reflect the currently selected tab. To have a given window display the same title no matter which tab is selected, you'll need to arrange to set the window title of all the tabs in the window to the same value.
As @KeithB mentioned, you can set the window title programmatically from within each shell or program running in a terminal via an escape sequence. If the terminals in the same window have something in common that you can key off of, you can have them all set the window title to the same (or a related) value.
You can also set the window title manually using the Inspector (Shell > Edit Title). If you do this and then save the terminal windows in a Window Group, the titles will be restored whenever you open the group.
Since you're setting up 20 terminals, I'm assuming you're already using a Window Group, but if you're not, look into it. You can set up your windows and tabs and save them so you can recreate them again later. You can even tell Terminal to open a given Window Group when Terminal starts (Terminal > Preferences > Startup). As of Mac OS X Lion 10.7, Window Groups can also automatically restore commands or ssh sessions created via Shell > New Command and Shell > New Remote Connection.
You can also customize the window title for multiple terminals via
Terminal > Preferences > Settings > [profile] > Window > Title
For each window, create a custom settings profile and customize the title. Create each of the tabs in a given window using the same profile (or assign the profile using the Inspector after creating the terminals). Then the tabs in a given window will all have the same title.
You can use custom profiles in combination with Window Groups, as well. Window Groups remember the settings profile of each terminal.
You can also differentiate terminals using different background colors or (in Lion) images, using settings profiles. Again, assign all the tabs in a given window the same profile if you want all the tabs in a given window to have the same appearance.