I've fallen in love with the sync function, it's perfect for someone like me who uses both a desktop and a laptop. I don't have to e-mail links to myself, I can just bookmark them and they appear on the other computer. It's great for work, and at the same time has loads of advantages for the spare time as well. I'm using it right now to keep track of a series I'm watching online; I've got a pinned tab with the next episode in the series always open.
The idea I got from here is a connected tab between two browsers. An example of how this would work for the end user would be like this: I'd open up a new connected tab, connect it to the laptop, go to the website where I'm watching the series, then close the browser when I'm done for the day. The next day I open my laptop to continue watching, and it opens the tab on the page I was on. This repeats, always updating on one computer whenever I go to a new URL on the other.
I know the simple solution to my specific issue is to simply open the screen showing what tabs are open on other computers and open the link, but I feel like a connected tab would be an interesting and potentially useful feature of Opera.