“…Lulu - allows authors to upload their manuscripts onto the site, where they can be printed off and sold individually as and when wanted.The same principal applies to other creative works that can be loaded onto the Lulu site, such as music, photos, calendars, and videos…one book can be printed off at a time eliminates the need for a minimum print-run to achieve profit, or indeed the danger of huge piles of remaindered copies being left unsold…”
Via BBC