Requires SilverStripe 3.3 (may work with other 3.x versions)
/thumbs/100/100 - Random 100 pixel square image /thumbs/100/100/faces - Random image from the faces folder /thumbs/100/100/faces/bo - Image called bo (Title) from the faces folder
Works well through a reverse proxy (e.g. nginx) to reduce load. Requires addition of cachebusting suffix to get fresh (random) image.