For a quick disposal cleaner pour white vinegar into an ice-cube tray and let it freeze overnight. After the cubes are frozen you can pop them out of the tray and put them into a freezer bag so they are ready to go. Anytime the disposal seems gross, turn it on and toss a cube down the drain. The ice helps to clean the blades and it helps with the smell too.
(don't you just love my cute little star ice-cubes? Dollar Store, yeah.)
But the real secret to keeping the disposal smelling fresh?
Lemons. Whenever I have a left over lemon wedge I toss it in the disposal (while it's running) and the sink is instantly unoffensive. Cool huh?
Have a very happy Memorial Day weekend!