Some more Discworld residents, The History Monks are the disciples of Wen the Eternally Surprised, the one man who managed to learn the true nature of Time (hint: it's a she...). They have the ability to "slice" time, or make time stretch. A very advanced monk can make a second stretch almost as long as an hour.
They live in a monastery hidden away in the mountains near the hub of the Discworld, (would you expect anything else?), called Oi Dong. It is encased in the perfect moment - a light spring breeze blows, the cherry trees are in bloom, etc. Among the secret chambers of Oi Dong are many scary looking dojos, the mandala hall (a room with a large sand mandala that tracks the patterns of history repeating itself), and the room where the procrastinators are kept. There are also many lovely gardens, including Lu-Tze's Garden of 5 Surprises (just what they are you'll have to figure out for yourself) where he cultivates his bonsai mountains.
And what do they do? They ensure that history happens. They take time from where it is being wasted, and put it to good use where it is needed.
Famous History Monks include: Lu-Tze the sweeper, Qu the gadget monk, The Abbot, and Lobsang Ludd. See Thief of Time for more details on the most secret society that never existed.