Almost everything has a limited shelf life in practice. The most critical on my list - medical supplies (including water purification tablets!), food, water, matches (wood or paper, both degrade after a few years), firestarters (some types deteriorate within a few years), batteries - alkaline as well as rechargeable, ammo etc.

High temperature, direct sunlight and high moisture all increase the rate of decay. Anything mechanical that isn't in use regularly must be checked every now and then. Also, a lot of folks seem to believe that syntethic materials are more resistant to decay than natural ones. Wrong - sunlight and UV radiation can affect many plastics and synthetic fibers in a very short span of time.