I don't think any special purpose software is needed. I have always done backups the "cheap and cheerful" way. It is even easier with Macs than it was on my PC.
I get an external hard drive. To back up, I plug it in, turn it on and then create a new folder in its root called todays_date_backup. Then I simply use Finder (or PathFinder in my case) to drag my home folder into my newly created backup folder. This copies ALL of my personal data. It does not create a full blown image of my current disk, but I tend to view the system setup as transient. It is my personal stuff (music, photos, files, etc.) that I want to keep.
To make this really useful, I use a system of two hard drives, which I rotate between work and home. Each time I do a backup, I take the hard drive with the fresh backup to work and exchange it with the one there. That way, I always have two full backups at two different locations. Hence, even if some terrible disaster should befall my house (tornado, flood, fire, whatever), I still have a full backup "off site".
Note that no incremental backup software is involved or needed. Hard drives are so big and so fast these days that this works great and it is so simple. It has always been my philosophy that in order to be done regularly, backing up must be easy. Apple clearly agrees with me - I think that this is the whole premise behind Time Machine (... a FAR more elegant solution than what I do of course!).
