Apple - How can I find exactly what files are included in my last Time Machine backup?

You could try BackupLoupe: it will give you the size of each backup, the backed-up files and catalog the backups with colors to quickly identify the big ones.

There are also lists of files excluded by rule or that you add manually to exclusions:

• On OS X, what files are excluded by rule from a Time Machine backup?

More recent app (10.9+) that does the trick: TimeTracker