Mac OS X has Timemachine. Mountain Lion supports multiple disks. USB or Timecapsule… netatalk is also an option.
If you have the possibility to backup at two locations you are maybe good prepared.

In case you don’t have the possibility you should take a look at crashplan for your offside backup.

Free version:

• backup to an USB disk
• backup to an network share
• backup to any other of your computers (LAN or WAN)
• backup to your friends computer
• de-duplication and compression

Payed version:

• backup to Crashplan servers
• backup sets
• 448-bit encryption

The backups are encrypted, it is possible to manage the key by your own and not upload it to Crashplan.

There are other online backup solutions out there. Ark, Mozy, Spideroak, … to name a few of them. Here is a more detail list for online storage Crashplan was more feature complete at the time I’ve look at it and the price was also ok for me.

The downsides:

• The client is Java based…
• You have to trust Crashplan. Closed source, proprietary network protocol, …

A few tips:

• The free version supports only 128bit encryption. So if you upgrade to the paid version you need to recreate your backups to take advantage of this.
• Backup sets give you the possibility to back up everything to a USB disk, but only your documents and photos to another computer. This saves you a lot of time for the initial backup. And let’s be honest… Not all the files on your disk are important 🙂