Dillo for RISC OS
Dillo is a Unix web browser. Here it is running under ChoX11, the X replacement library, as a proper RISC OS application.
RDesktop
RDesktop is a remote desktop client, for use with Windows machines running Windows NT Terminal servers, and allows remote desktop sessions in a similar manner to VNC (but much faster). RDesktop is also using ChoX11. Both RDesktop and Dillo are unmodified from their original sources.
The Gimp
The GIMP is a popular and powerful image editing program, similar to Photodesk and Photoshop in functionality. Despite appearances, this program is not running in Windows - the program is running in RISC OS and displaying on a Windows X Server, as that was easy at the time. It could equally run under RiscX.
Lynx, Links and W3M running at the same time in RISC OS
The picture shows the three most well known text browsers running at the same time. They're all hosted by Nettle taskwindows.