Back to topic:
I've been thinking about this kind of solution:
- Keywords [days], [weeks], [months] and [years] in the summary or description would be replaced with the number of days/weeks/months/years to or from the event's start date (or due date for the tasks).
- Alternatively you could also define the date e.g. [days=20080101] or [years=1960] if you want to use it in a single event.
- A dynamic counter could be done like this: [days=today]. It would calculate the number of days from today to the event's start date (i.e. the value would change every day).