Ask TUAW: how do you maintain your Mac?

Last Friday a reader wanted to know how the TUAW community keeps their Macs and their displays clean. This week I figured I'd post a reader's question about maintaining a Mac under the hood. I lost the reader's email, so I apologize to whoever sent in the question, but here we go with this week's Ask TUAW: how do you maintain OS X? What cleanup apps do you run? Do you check your permissions once a month or is DiskWarrior a daily habit? Do you backup, wipe and reinstall OS X often or have you been upgrading through every version since 10.0?

Personally, since I'm on Tiger I've settled into using the Maintenance 3.0 Automator action. I've tied it to start up on a weekly repeating appointment in iCal, so I never forget to run it.

But what about you, dear TUAW readers? How do you keep your Mac humming along?