Savings stamps are still redeemable at face value if you can find the right place (I believe it is the Treasury Department, Bureau of the Public Debt). Unlike Savings Bonds they don't accrue interest (and unlike savings bonds, they tend to be redeemable by the bearer and not tied to a specific individual). Faster, easier, and probably a little more selling on
ebay at least when the books are not too full - the stamps are abundant but there are numerous varieties of the booklets and they are collectible (I have a 10 frame large gold medal exhibit of this stuff).