Oddly large incremental backups

[Asgeir Bjarni Ingvarsson]

Is there a way to see a diff for an archive or a list of changed files 
that have been included?

I'm consistently seeing a backup size of ~300MB when I'm expecting much 
lower numbers. I have excluded obvious noise sources such as browser 
cache, but I'd really like to get a list of uploaded files so I can see 
what exactly is causing the backups to inflate like this.