It may be obvious, but many of these utilites are themselves compressed into the ZIP format so they assume that you already have a ZIP decoding utility. Most browsers for Windows includes this.

WINZIP - .zip Decoder

WUUDO - UUENCODE .uue Encoder/Decoder

Stuffit Expander - Decodes .sit/.zip/.gzip/.arj/.hqx/.uue

WINZOO - .zoo Decoder