[Tim Wood]

Just to consolidate the info; the files we currently write are:

~/Library/Preferences/com.omnigroup.OmniFocus.plist -- your preferences
~/Library/Application Support/OmniFocus -- current "real" document + perspectives
~/Library/Caches/com.omnigroup.OmniFocus -- optimized cache; can be blown away when OmniFocus isn't running and it'll get rebuilt
~/Library/Caches/Metadata/com.omnigroup.OmniFocus -- Spotlight index files; can also be deleted when OmniFocus isn't running to force a rebuild.
~/Documents/OmniFocus Backups -- default location for periodic backups
~/Library/Application Support/Quicksilver/Actions/Send to OmniFocus.scpt -- installed at launch
~/Library/Application Support/SyncServices/Local/clientdata/com.omnigroup.OmniFocus -- installed on our behalf by SyncServices; shouldn't touch this directly