The Toaster is a tool that takes something and pops it back up when you need it. When you are going through your Recipes and something needs to be deferred to later, you use the toaster. There are several ways of doing this. In some cases, your Master Planner will function as your toaster, as some sofware will notify you when something is due. But you might want to do something at the beginning of your workflow with things that are being put off for a while. If you're using Gmail, Boomerang is a service that can reschedule emails to a later time. If you are dealing with paper, the "Tickler File " from GTD not only has a provocative name that makes you giggle, but is one of the single greatest time management ideas ever.
I use Sanebox for an electronic tickler and a set of 42 Folders for paper.