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I use Time Machine, SuperDuper to a network drive, and Carbonite for on-line backup (use Carbonite for my iPad and iPhone too).
 
CrashPlan, SuperDuper! and TimeMachine here. Not everything for every computer (I've got 7), but important items are backed up on all three methods.
 
SuperDuper to multiple HDDs.

Anyone with anything they value on a computer should have multiple backups. We get threads on a regular basis from people who where their HDD crashed or they mistakenly deleted all their pictures or whatever and want to know how to recover...

the way to recover is to use a backup.
 
Duff-Man says...well, duh. I let Time Machine do it's thing but also do some clones with Super Duper every couple of weeks or so, or at very most before doing any major software installs/upgrades...if you don't you're asking for trouble....oh yeah!
 
Well, not new to computers & BU strategies, but just obtained a new rMBP - this is my personal computer (in retirement) - files are not critical, so doing Time Machine on an external HD, AND also double BU of my Docs/Music/Photos onto a La Cie external SSD.

NOW, about to obtain a new iMac (mainly for the wife) - will do Time Machine onto a Seagate I TB HD and also Cabonite online - BOTTOM LINE - a single BU option is not enough for important files, AND if these are crucial then offline storage is a definite consideration (who knows, your house may burn down?) - :)
 
I use TimeMachine to a NAS, and Carbon Copy Cloner to a couple of external disks, one of which is a portable disk that I take offsite.

I like TM for those moments that I deleted a file/folder and CCC for full system restores. I find CCC much faster to restore my entire system then TM - as usual YMMV
 
Time machine backup to a portable hard drive, more important stuff goes on Dropbox, encrypted with BoxCryptor.
 
TM to a partitioned 2 TB WD USB 3 external and CrashPlan for off-site. My VM isn't backed up as I only use it to access data that's already backed up through other methods (Truecrypt volume that's shared from OS X to the VM, contains financial docs and is backed up itself).
 
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