ArcEm - The Acorn System Emulator
Computers, Emulators, Acorn, Archimedes - ArcEm. An A4xx-series emulator for UNIX/Linux, RISC OS and Windows.
https://arcem.sourceforge.net/
Wocki's Acorn Emulation Site
Computers, Emulators, Acorn, Archimedes - Wocki's Acorn-Site. Includes downloads, pictures of box covers and a message board.
http://acorn.revivalteam.de/
Riscose home page
Computers, Emulators, Acorn, Archimedes - Riscose. A RISC OS emulator that runs under UNIX.
https://riscose.sourceforge.net/
VirtualAcorn
VirtualAcorn, turn a Windows PC into an Acorn Compatible, comes complete with RISC OS
http://www.virtualacorn.co.uk/