Instant Updating Stock Quotes
Visit this news story between 9:30 AM and 4:00 PM EST during a weekday. I really don't care about the content of the story -- I'm just amazed that those stock prices tick in "real-time" (15-20 minutes delayed, but they still update as time goes on). That's really cool. I wish more web sites did this for data like weather and sports scores. You could even write a whole article in real-time like this, though I imagine some people might get upset if facts were suddenly redacted or changed as if nothing had happened.