The Great Outlook Cloudmark Crash of 2007 got me thinking about backing up your emails.
Sure, Outlook has got an archive feature and even a backup plugin for your personal folders (Outlook 2003/2002). But this obviously wouldn't work if that software itself was the one that crashed, or if your computer's hard disk bit the dust.
Enter GMail: Turns out you can configure it as a backup of sorts (and still let you use Outlook in a normal way). In GMail's Settings > Accounts tab, you can ask it to get mails from your other email accounts, fetch and store the emails (directly to the Archived folder, bypassing the inbox), and leave a copy of the emails on the server for your Outlook to fetch later on.
The tutorial from Gmail's Help Center has a step-bystep direction on how to do this: Link
If you don't have a GMail account, you can get one for free directly from Google.