I need to give a friend who has a Mac a bunch of files. Compression doesn't matter, only ease of use. What archive format do you recommend such that no 3rd party tools are needed for extraction? Zip?
Gzipped Tarball. Should work anywhere.
(or right-click and "Compress", "Archive" on many distros)
(or double-click on a Mac)
Archive Utility, which is part of Mac OS X, supports tons of formats for extraction, among these: