All right, so "Girl Power" was more about retail than revolution. But if they aren't exactly feminists, the Spice Girls have always been advocates for friendship, a message young girls are starving for. Female bonding is the glue that holds this greatest hits collection together. "Mama" is obvious, but tracks that aren't specifically about friendship also sound like a fun, friendly night out with the girls. And with all the Girls trading lyrics, even romantic tunes like "Too Much" seem to reiterate the philosophy of "Wannabe": If you wanna be my lover ... well, you know the rest.