The 2 major sites for ftp'ing Mac software are sumex-aim.stanford.edu
(usually referred to as "info-mac") and mac.archive.umich.edu.

However, these two sites are so incredibly busy that they are nearly
impossible to connect to (in fact, info-mac no longer accepts direct
ftp connections), so you will need to use a mirror site such as
mirrors.aol.com.  A mirror site is a site that contains an exact copy
of the contents of another site, in the hopes of diverting some traffic
away from the more popular site.  Mirror sites are usually updated 1 to 3
days behind the "mother" site.

Other mirror sites of info-mac and umich exist at grind.isca.uiowa.edu
(North America), archie.au (Australia) and nic.switch.ch (Switzerland).
It's more polite and generally faster to connect to a site that's on the
same continent as you are.

Wherever this FAQ points to a file at info-mac or umich, the URL
(Universal Resource Locator) given is for that file's location at the
AOL mirrors.  This is because the AOL mirrors are fast, reliable, and
frequently updated.  It's also because the FAQ maintainer enjoys the idea
of Usenet taking advantage of AOL for a change, instead of the other way
around.

Bruce Grubb periodically posts a comprehensive list of Mac ftp sites
to comp.sys.mac.games.  It is available via ftp from info-mac in
<ftp://mirrors.aol.com/pub/info-mac/info/comm/> and from umich in
<ftp://mirrors.aol.com/pub/mac/misc/documentation/>.  There is an HTML 
version at <http://rever.nmsu.edu/~bgrubb/mac-ftp-list.html>.