Kevin Wu's Graph TV

UPDATE! This website is not currently available. 

Kevin Wu's Graph TV  uses individual episode ratings (archival data via IMDB) of TV shows, graphs each episode over the course of a series via scatter plot, and generates a regression line.

This demonstrates fun with archival data as well as regression lines and scatter plots. You could also discuss sampling, in that these ratings were provided by IMDB users and, presumably, big fans of the shows (and whether or not this constitutes representative sampling).

The saddest little purple dot is the episode Black Market. Truth!