Diary  
   Simple journal keeping, with output in various formats, including HTML.
   http://www.mikejs.com/riscos/diary.html

Stephen Murphy's Software - MakeCal  
   Generates wall planners/calendars in Draw format
   http://web.ukonline.co.uk/stephen.murphy/

Explan Diary Software  
   Formerly commercial products, the Event diary and two types of the networked Occasion diary, are now FreeWare.
   http://www.explan.co.uk/Diary.html

Chris Morison's Risc Organizer  
   Desktop personal Organizer for Acorn RISC OS Computers. It contains all the main features of an Organizer - calendar, diary, anniversary and address-book sections within a simple, user friendly graphical interface.
   http://www.organizer.ukgateway.net/

RemindMe  
   For people working in a busy environment, where major tasks can be easily overlooked in favour of minor ones.
   http://homepage.eurobell.co.uk/katech/cherisha/products/remin.html