Of all the personal planning tools I have tried, the only one sticked and is measurably improving my daily life of a freelance software developer: FollowUp.cc.
Of all the personal diary tools I have tried, the only one sticked and is used — well not daily, but fairly often: OhLife.
OhLife is fun because it emails me every day, so I can skip any days I like knowing that eventually I will write again. The default outcome for other diaries is exactly the opposite (you stop writing), so a guilt builds up as you skip days.
The power of FollowUp is that it does not try to be your todo list, and the reminders only fire once. You can move them with one click (which is very important), but you don’t have do anything if you no longer care.
A recipe for a successful productivity tool is to take away the problem, but avoid adding any pressure or maintenance:
Expect and encourage the user to start small. One entry, one task, no pressure to do a braindump.
Don’t put pressure to use it regularly. Should not be a mess when I come back after ignoring it for a month. But can’t also irreversibly forget things unless I act on them timely.
I’m yet to see someone solve this for news, RSS and twitter, which either accumulate unread items or loose old results forever. I think FollowUp’s found a sweet spot by focusing on future events, but keeping the old ones accessible on the calendar (and in email archives).
Consider e-mail as the primary UI for your next little project.