I was thinking more something that you "create" as it's own entity, then add to over time, and people can come back to it. A more personal version of a tag, that has it's own unique ID, that only you can add too, and that keeps all it's posts as a list that you can see previous posts on and such.
I think you could achieve that with a personal tag. But, I admit that personal tags were much better put to that purpose before they were created by default. It's very likely that we will return to the old system of two tags and a community tag soon. As before, if the author so desired, she could make one of the tags a personal one. We have also envisioned a version of saved posts where you could create categories for them. We call them archives. thenewgreen has been lobbying for them for years. :)