Having used Opera on Windows for quite some time now, there’s a lot of login data saved in Opera’s wand.dat. Unfortunately, it can’t be accessed out-of-the-box. Three ways to get your passwords back:

• Use an appropriate bookmarklet to display all passwords on the current page
• Use the shareware google reveals when searching for the obvious ‘opera password‘. Never tried this piece of software, though.
• Find a little tool called unwand. It can export all data stored in wand.dat to a text-file for further processing. Runs with Wine, too.