My first character was on her way towards Skyborn Altar with Vilkas on that quest where one of the brothers wants to kill a dragon with you (Dragon Seekers, I think it's called). Between Stonehills and Labyrinthian, a random dragon attacks us, and I suddenly hear someone yell "somebody help!" In a helpless voice.
It did sound like Vilkas, but since he shares voice with a lot of NPCs ("male Nord"), I looked around in case this was some strange random encounter or quest I just stumbled over. I heard it afain, and sure, it WAS Vilkas, who apparently had turned into a total wimp at the sight of a dragon.
My character sighed, rolled her eyes and said something about how it takes a woman to get things done, then she went to fight the dragon.
That happened to me outside Whiterun. I'm pretty sure the one who said was the same guy who did the jump-on-dragon's-head killmove.

All (or at least most) generic voice types have comments if you walk around naked. I got the "unseasonably warm" comment from the fletcher in Solitude (who shares voice with the Jarl of Falkreath) - after that his goodbye phrase "perhaps I'll be seeing more of you" has a completely different meaning to me...
My favorite "naked" comment was probably when my hot hot Dunmer "accidently" walked in naked at the New Gnisis Cornerclub and the Dunmer owner dryly remarked that "you're not as attractive as you think".
She decided he was just jealous that he couldn't get her.
