Keeping with the childhood nostalgia theme a few posts back, boingboing.net has a post of Sesame Street segments that creeped people out. While the robot S.A.M. didn’t make me nervous (I strangely wanted to touch the material they used for his mouth) I have to agree with the comment from David Z: that orange singing Carmen made me uncomfortable too.
There was also a cartoon segment of 30 dots that use to make me crazy with anticipation. I think there were at least 3 or 4 different versions and one ending use to make me climb the wall.