In this show we talk about Amazon Spot Instances. The story story: they are Amazon servers with their own little economy. You bid on them, like you would at auction. There is no guarantee you'll get to keep the server. Get outbid, and it'll spin down. It's based on the empty server space that Amazon needs to have available to guarantee expandability and bursts of growth and the like.
Can you save money using them? Absolutely. We do. Counter-intuitively, we even use spot instances for mission critical stuff like our web servers. Is it like selling burnt edges of barbeque? uhm. kinda.