I use a bunch of Google services, but what if the whole thing comes crashing down and I lose my data? That’s why I back up everything I can back up. I have scripts to automatically pull my calendar data out of Google and stick it in my incremental backup, I’ve set up mail systems that route my mail so that I always have a local copy of whatever has gone through Google and I even back up my RSS reader subscriptions.
Here’s a small thought, though: If Google offered a guaranteed service, where they would be required to provide a certain level of safety for my data, I’d pay something for that. Maybe USD 100/year would be the sweet spot.
They offer similar things for corporate customers where e.g. Google Apps (and associated calendar and mail functions) cost USD 50/year per person, but I’d like this sort of thing for private users.