This is an extension of the possibilities calendar idea.
I’m afraid I’m neither spontaneous nor very creative when it comes to fun activities. I need ideas at hand. I am in the process of writing some activities ideas (more lists) for myself and the little fella. These include things to do at home on a rainy day, free stuff out and about (but within walking distance), free stuff we need the car for, and activity ideas that aren’t free (like visiting the bird sanctuary). These are activities that we can do anytime as opposed to events and activities in in the possibilities calendar that are time based.
I actually used to do this a few years ago with DH. When we had ideas for activities or places we’d like to visit, they would be added to the list. Well, my activities list is back, but much more child related.