Of course I do backups and I recommend strongly that you do too. A good percentage of my billable hours are spent on making sure that clients' backup systems are operating correctly and backing up what they're supposed to. Some of these systems can be quite complex, firing off at specific times, moving data from one location to another, even synchronizing servers.
But... most of my "backups" of my laptop were really clones done whenever I got that funny feeling in my stomach (it's a very different story for my servers and desktop). Mac OS X Server can offer a destination for Time Machine backups, and since I keep a server running in my house it's just silly that I hadn't set it up to do the work (and this can be done on a server or on an AirPort or a Time Capsule, even some NAS devices). Several months ago I configured my laptop to use a server-based Time Machine. Of course I assumed I'd never need it and I kept doing clones at the same pace I used to. I assumed I'd never need to worry about that - sound like your thinking too?
Friday I ran a neat little AppleScript to anonymize a machine for a client. The script removes users, resets a machine to a clean state and blows away the local KDC. For the first time the script malfunctioned and instead of working on the client's machine it started to work on MINE! I have no idea how extensive the actual damage was, but I could see enough to know that what was left of my data was in bad shape. Needless to say, I was, ummm... tense.
When I got home I booted from the Mac OS X installer disk, started the utility for recovering from Time Machine and logged into the server to show it the source. A few moments later and the machine was asking me which date I wanted to restore from. Thank you, 8:49am from that morning will be lovely! 2.5 hours later I was back to where I'd started from.
There are many, many backup programs for the Mac. Time Machine is part of the OS and it works very, very well. You can get a nice big external USB drive to store your backups on for $50-$150. It could well be your best accessory for your Mac.