I don’t know since when Opera.com has it but I just noticed it now: an affiliate program. It seems to work as always: Place a link on your site and when someone follows this link and buys a license you get some money.
The money you’ve earned is paid 4 times per year. You have to earn at least 20USD to get a payment. If you didn’t get up to this threshold the amount will be added to the money you get in during the next quarter year.
I couldn’t find anything that indicates that you’re not allowed to have links to rival products on the site so it could be an option for me ;-)