I'm the author of some applications for Psion computers:

• KbdMap allows you to customize your keyboard layout on S3/S3a/3c/Workabout computers.
• Undelete helps you if you have deleted files on a Flash SSD.
• HexView is a hexadecimal viewer/editor for files and memory segments and more. A tool for programmers and hackers.
• RShell is a file manager. It was with Ranger Disk support, but currently this feature is disabled. Compatible with Series 3a/3c and Siena.
  Beta version of RShell with Ranger Disk support is available now!
• Printer driver for LQ printers allows to use wide range of fonts on Canon and Epson LQ printers.