> Their browser, surf, doesn't even support tabs as far as I can remember.

There is a general tabbing frontend that allows you to tab all sorts of applications: http://tools.suckless.org/tabbed.

I've never used surf, but I really do like tabbed. It plays super nicely with most tiling window managers I've used, and lets me get the single best feature (ymmv) of i3 on xmonad.

Could you elaborate on how you use tabbed with i3, and how it's better than simply using i3's native tiling features?