One of the most helpful features of Amazon is thier "Subscribe and Save" option when buying things. I have found it most useful for things that are consumables, but that are not frequently needed. The two most helful items: Windshield wipers and shower curtain liners.
Those two items are always the things I notice need replacing when I am not in a position to order them (I'm either naked or driving). Placing them on subscribe and save, they just show up at pre-defined frequencies and I swap them out. It is amazing. I haven't even thought about those things in years.