I'm quoting Chartbuddy, a charting bot operated by a former Bitcointalk participant named Richy_T who posted here hourly until a couple of months ago. He had a falling out with BCT's administrator over what he considered to be unfair censorship in the blocksize limit debate and took his bot elsewhere.

Basically it shows a graphic depiction of the recent history of the order book at a given exchange, in this case Bitfinex. Originally a new line was added every minute  and the chart was posted hourly. Now it is posted every 3 hours.

I like to use it to see in retrospect what has happened in price swings.
_____

While I was typing this, I see we just reached a new All Year High. Hooray!