I think there are a few good permissions workbooks floating around.  I made this one a while ago for personal use, but it wasn't until the readonly user was released in 8.2.5 that I felt I could post it here.

Like Andrew Macey's workbook, it only shows explicit permissions.  There's no evaluation of effective permissions here.  But it is potentially nice to see it all in one place.  Excluding the "All Users" group (I've saved it that way) reduces the visual complexity

This TWB connects to localhost, assuming you're running the workbook on the server.  That can obviously be changed.

Remember that this only works in 8.2.5 when the readonly user is enabled, per Create Custom Administrative Views. Prior to 8.2.5, you'll have to use one of the unsupported methods to connect.