A quick plug for git if you're a Max developer.
I've been using the open-source distributed source control system git to manage my Max programming and it's been a total winner for me, even though I'm working on my own.
Knowing that I'm a few keystrokes away from the last few good states of my system allows me to take all sorts of risks that I'd never take otherwise.
I only ever use git init, add, commit and checkout commands but it's still incredibly powerful. Check it out if you're doing serious development.
(Of course, I make offsite backups too :-D)