Here's a further suggestion for the Google+ Profile. It's based on the old look, before the UI update. But the idea is the same. An archive of all past posts, with the ability to make this "tab" visible to others, would be so valuable for finding old posts. I based it on Blogger.
The original mockup post is here: https://plus.google.com/100152754393360938972/posts/QnjweQYgDB9