Trent on The Simple Dollar details how he switched to using an empty hand lotion container to store his shampoo and in doing so eliminated three out of every four shampoo bottle purchases he was making per year. One pump gives him the exact amount of shampoo he needs.
It's not a huge savings, but simple frugal moves can really add up. Plus, a pump dispenser saves you the time waiting for the shampoo at the bottom of the bottle to be dispensed.