I haven't really found anything that I like. What do people use?
I used to have a psion, and liked "mentor" a lot (mentor page). This automatically scheduled tasks in a fairly sensible order, so each day it would give me a list of things to do. Each task had a rough duration associated with it so rather than just showing a never-ending list of jobs it would suggest (say) 3 things to do today, and schedule the less urgent tasks for future days. If today's tasks didn't get done, then everything would be shuffled back semi-automatically, but jobs would not be pushed beyond their deadline (without user confirmation). It also handled fixed appointments, although i don't have many of them.