If you look at your ~/.thumbnails directory in gnome, you might find out that there are tens or even hundreds of megabytes wasted to thumbnails of files that aren't on your system (thumbnails of files that have been moved or renamed, were on removable devices, ...). Since I'm always running out of diskspace, I'd like to "fix" that. There are several "easy" solutions: delete the whole contents of the directories in .thumbnails. But then the "good" thumbnails are gone too, and they all need to be rebuild while you're browsing your filesystem.
