Titanium Backup might be the single most important app you install on your rooted device. It also provides priceless peace of mind, so that when your phone dies in a tragic, toilet-drowning incident, you can easily restore all of your data to a brand-new device.
In its default mode, the app backs up all of your data to your phone's SD card. But connect it to a Dropbox account, and you'll be able to push all of your data, apps and even system settings into an online lockbox. Then, in the event of a data disaster, your critical system setup and information will be secure and ready for installation to a new phone.
Don't think of this app as optional. It's a necessity, primarily because when you're constantly altering and tweaking a rooted phone, there's an increased chance of causing a snafu that results in data loss. By backing up, you'll add a layer of safety for your data and possibly save your sanity, too.