http://free-backup.info/
A powerful, easy-to-use freeware zip and unzip utility, EasyZip offers a good interface and all the bells and whistles of the most popular commercial archive programs. This program features integration with Windows (including extracting archives and zipping files directly from Windows Explorer); checking for viruses in archive; drag and drop; and more. (For Windows).
http://www.camunzip.com/
The classic decompression tool for the Mac is now available for Windows users. An easy-to-use free utility, StuffIt Expander can handle any type of compressed file you throw at it, including .zip files. It'll also handle uuencoded (.uue), BinHex (.hqx), and MacBinary (.bin), ARC (.arc), Arj (.arj), and gzip (.gz) formats. (For Windows and Mac).