Rhub offers a few ways to aggregate feeds.
Group administrators can allow group blogs to be published that aggregate each user's blog. This only works of course if people have set their blog address, and their permissions permit it.
This feed is accessible from the 'Feeds' button that appears on the bottom of group pages.
To aggregate a bunch of feeds, create bookmarks for them, set their feed address, and add them to a set. Note feed items will only appear if the set contains only bookmarks.
See also
Categories: Feeds | Help