Calendar and contacts: What if you don't use iCloud, but you have synced your calendar and contacts to your still-functional iPhone? In that case, create an iCloud account if you don't currently have one, sign into it, and ask your iPhone to sync your contacts and calendars with iCloud. When you later want that data on your Mac, just create an iCloud account on it, configure iCloud to sync contacts and calendars, and your data will appear on your Mac in short order.
Your camera card
Do you regularly delete images from your camera card? If the answer is "no," today you're in luck. Keep those cards available, so you can download the images to your new or repaired computer.
Know any other unintentional backups that might cheer up a fellow Mac user suffering from hard drive failure? Share your tips in the forums.