What is written about the hardware is true also for the software.
The impressive amount of material required to make a selection.
The versatile offer makes choosing difficult.
Roughly speaking, the categories below can be recognised.

• Program languages and the courses
• Basic and basic extensions
• Forth
• Pascal
• Lisp
• Assembler (macro-, symbolic-Assembler - Salfaa-)
• Utilities (A huge number of,
  From sourcemakers up to tape and disc (visa versa)
• Educational
• Visualisations, mathematics.
• Constellations
• Atomware I,II,III. Disassembling-lists from the complete basic interpreter (#Cxxx),
  the floppy-controller (#Exxx)and the Operating system (#Fxxx).
• Communications
• RTTY (telex)
• CW (morse)
• Fax en Hell
• Games ow.
• Chess
• Checkers
• The common (arcade) Games
• Flightsimulators (Schiphol and 747)
• Bankswitching systems (to control the "schakelkaart")
• AXR2 system from Delft
• Branquart system
• Het CX-System
• Graphic-extensions (the GAGS-box)

To my mind, a few highlights need to be mentioned here.
In alphabetic order: the assemblercourse by L.Bijnagte, the P-Charme interpreter (basic-extension and utilities) by F.v.Hoesel, the symbolic assembler Salfaa, the Atom in PC software from R.Leurs and last but not least the Atom-Emulator for IBM-PCs by W.Ras.

Of course, only a summary can be highlighted. Some from it can be found on the download-page. On the link page are links to the sites from R.Leurs and W.Ras showing their products. In addition to the products from Acorn there are quite a number of publications and books and a row of issues from the Atom usersclub.