Firefox and Iceweasel, when encountering a news feed, display a page that allows the user to subscribe to the feed, using Live Bookmarks, Google Reader, Bloglines, My Yahoo!, or an external reader program. The list of available applications comes from URIs and titles in the preferences, under browser.contentHandlers.types.*. For the benefit of people who use aggregate as their feed reader, the ikiwiki CGI could expose a URI to directly add a new feed to the aggregated list; this would allow users to configure their browser to subscribe to feeds via aggregate running on their site. We could then provide the manual configuration settings as a tip, and perhaps provide an extension or other mechanism to set them automatically. --JoshTriplett