The first thing anyone who is looking to download software from ftp sites on the net should do is to read the FAQ. The best reference I've seen online on how best to do this sort of thing was originally compiled by Nathan Mates. It has been reorganized and can be found at http://www.gno.org/pub/apple2/doc/FAQs/.
Once you've studied up and have a good idea of how to properly download and unpack files from the net, then try these sites:
DAR Systems International - Adventure game software for the Apple II and IIgs, from Eric Seiden and his associates. Titles include:Mines Of Moria and Mines Of Moria II (The Sequel), The Pits Of Doom!, Realm of Altair Series, Gem Of Zephyrr, Sword of Altair, Quest For Varsar Trilogy, Sable Powers Rising, Casino Games, and the famous ProLine BBS package. All are legal downloads from DAR Systems and their copyright holders. http://www.darsys.net/dsi.html
Apple II Software from Apple - Apple maintains an archive of 8-bit and 16-bit software for the II and IIgs. The selection ranges from the last release of GS/OS (System 6.0.1), HyperCard IIgs v1.1, Apple II system utilities, and ShrinkIt v1.1. You'll need to run Mac OS on some machine to unpack these archives.
AV Systems Software - Richard Hall, the current owner of AV Systems Software has placed all of the company's Apple II titles into freeware status. These programs which contain distillations of public domain software are mostly DOS 3.3 based, but should run under ProDOS. They can be downloaded from his ftp site: ftp://22.214.171.124. Use the login name AVSystems and note that it is case sensitive. Since no password is required, just hit "return" at that prompt.
Free Software for the Apple II - Gareth Jones (http://www.intergate.ca/personal/gslj/index.html has taken on the monumental task of codifying much of the DOS 3.3, ProDOS (8-bit) and IIgs-specific (16-bit) Apple II software that has been reclassified and released for free downloading. You can access this site at this url:
Marinetti - Marinetti, the brainchild of Richard Bennett is the only TCP/IP stack available for the Apple IIGS, clean room developed from the RFCs, and written completely in 65c816 assembly language. Marinetti supports TCP, ICMP, UDP, IP, custom datagrams, plug-in link layers, SLIP (includes scripting and up to 57600 serial speed) and an easy to use IPC interface. More information can be found at http://www.apple2.org/marinetti/
Marlene - Marinetti users should check out Kelvin Sherlock's new program, Marlene, a color VT100 telnet utility for the Apple IIGS. Users should note that besides Marinetti, this programs requires a GNO/ME or ORCA compatible shell. Kelvin has also released a utility to help the user more easily connect and disconnect Marinetti to their system. More information can be found at http://iigs.ksherlock.com/ .
Complete Pascal (Formerly TML Pascal II) - Apple II stalwart and programming legend Paul Zaleski has created a comprehensive resource for those looking for Apple II programming resources that utilize the Apple IIgs Toolbox and the Pascal compiler. The site includes downloadable ShrinkIt disk images for Complete Pascal 2.0. More information can be found at http://www.snowcat.com/a2programming/ .
Trenco Apple II Archive - In late 1997, a group of Apple II users and programmers decided to open another ftp archive site, plus mirrors. The master ftp site is hosted under the gno.org domain. It is accessible either by ftp or by http:
For FTP access, you should log in as "anonymous" at ftp.gno.org. This site does allow uploads to the directory ftp://ftp.gno.org/incoming.
Software from Lazarus Long http://www.lazilong.com/apple_II/ Long time Apple II stalwart Laz Long has made many of his creations Freeware or inexpensive shareware. A2snipper3.0 and an installer for Bird's Better Bye are available for the Apple II, and a variety of Apple II utilities for the Macintosh - a2pix, ImageConverter, Apple ][ Font, and the powerful Apple DOS File System for mounting any Apple II disk image type, are also available.
Neil Parker's Collection of Apple II WWW and FTP Sites This is a terrific site of working hyperlinks and information to finding Apple II software online. Well maintained and frequently updated.
Ninjaforce - Jesse Blue is back! Animé, Asimov (a disk image utility), Deskplay, Megademo, Picture Ripper II, Revenge Of The Bobs, and more is now available for download from the Ninjaforce web site. http://www.ninjaforce.com/html/products.html
Ground - the Apple II/IIgs Software Archive at the University of Iowa
A mirror of the original Ground web collection can be found at http://www.apple2.org.za/mirrors/ground.icaen.uiowa.edu/
Nova Scotia Apple U.G. Archive Lots of files and information areas for both the Apple II and Apple IIGS.