Crash Plan already offers this: http://support.code42.com/CrashPlan/Latest/Backup/Seeded_Backup http://support.code42.com/CrashPlan/Latest/Backup/Seeded_Bac...

Crash Plan already offers this: http://support.code42.com/CrashPlan/Latest/Backup/Seeded_Backup http://support.code42.com/CrashPlan/Latest/Backup/Seeded_Bac... As I believe many larger backup services do nowadays.