Just had to do this on one of my sites, with a list per portals. Just add the following script to a reports module, and you have a live view of the usage of your modules. This script will give you a table with the following columns: ModuleName, Module Friendly Name, PortalName and PortalID:

SELECT     DM.ModuleName, MD.FriendlyName, P.PortalName, P.PortalID
FROM         {objectQualifier}Modules AS M
    INNER JOIN {objectQualifier}ModuleDefinitions AS MD ON M.ModuleDefID = MD.ModuleDefID
    INNER JOIN {objectQualifier}DesktopModules AS DM ON MD.DesktopModuleID = DM.DesktopModuleID
    INNER JOIN {objectQualifier}Portals AS P ON M.PortalID = P.PortalID
WHERE     (DM.IsAdmin = 0)
GROUP BY DM.ModuleName, MD.FriendlyName, P.PortalName, P.PortalID

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