This is more difficult than it sounds. The curation part, anyway. "Important" is a pretty subjective, and flexible, term. Something that might seem innocuous now could well have far-reaching ramifications twenty years from now.
Agreed. I tried a 7 day most popular section on http://skimfeed.com and I just couldn't get the algorithm personal enough to be useful. 24 hours seems to be the sweet spot for users.