Nothing too great has happened to me so far, though I did run in to a child kiting a spider from who-knows-where. On my way to Ivarstead, ran past a mill I figured I'd discover, and on my way through a little girl comes running with an angry spider chasing her. First time I've even seen a spider out in the open.
There's also a scripted conversation during the main quest where they used the same voice actor for both parts. I assume that's what they've done, or it's one guard talking to himself while another guard listens.
There was also the time I did a Dark Brotherhood quest - I killed the target and remained unseen, but then someone sent to "help" runs up and talks to me, and suddenly I have an angry mob chasing me. The guy sent to help me just wandered off. I didn't even get the bonus for the job, even though I did it the way they wanted me to