I recently found fast, reliable, lightweight zip/unzip utility from http://www.info-zip.org/. I've use this tool extensively, and one of main reasons is that can handle files larger then 4Gb, which was main limitation of older zip tools (I think that zlib has this limitation). There are two executable's: zip and unzip. (use -h or -? to get help).

Downloads:

unzip60.zip version 6.00 source code
zip30.zip version 3.00 source code
zip.exe version 3.00 win32 build
unzip.exe version 6.00 win32 build

Examples:

zip  new.zip file.txt - zips file.txt into new.zip archive

zip -r new.zip Dir1 Dir2 - zips whole content of the directories named Dir1 and Dir2 into file new.zip (-r recursive inside directories)

unzip -o new.zip - unzips content of new.zip, overwrites existing files without asking and recreates saved directory strucure (-o overwrite)