For me the dream team was GReader combined with the PostRank (Chrome Extension) to filter based on social metrics. Unfortunately PostRank was the second most important product that Google is its wisdom (and evilness) decided to shut down. For an idea of the power see: https://spreadsheets.google.com/spreadsheet/lv?key=tWri7T3f4.... Each row of the GReader would be lighter or darker based on the PostRank or you could simply filter based on minimum PR rating.

The one and only enhancement beyond this would be to integrate an Instapaper-type functionality so I have all my content in one place, whether fed by RSS, or random pages that I tag to read later as I come across them.

Digg is one of the few companies that I could see pull off the social dimension successfully.