I just had an idea for dungeons or caves, which I guess could fit in with the quest system. I was thinking of having a few randomly spread around the world, with ring level enemies inside. It'd be neat to be roaming around and find a cave that has a sleeping bear inside, or a group of bandits. And then when you clear it out, they each have their own respawn timer of I dunno, a few hours, and then something else comes in.
I also thought of a few new enemies, like lynx, wolves and badgers. I'm not sure if you're gonna go a more mythological route and include things like dragons, or else I'd list those too.