TagTeam is an RSS / Atom / RDF aggregator with the ability to filter and remix its input feeds with a high degree of flexibility. Items can be added directly to TagTeam “bookmarking collections” via the provided delicious-like bookmarklet, and these items can be remixed and filtered like any other item.
TagTeam can aggregate content from anything that emits RSS, Atom, or RDF. This includes delicious, zotero, WordPress, twitter, mediawiki, connotea, blogger, github, and too many other applications and services to mention. It uses the feed-abstract gem, written as part of this project to create a better way of dealing with structured feeds. feed-abstract understands some generators and does magical things - like turning twitter hashtags into actual tags on aggregated items. Has its own search engine.
Written in Ruby on Rails, uses Postgres as its backend. Redis for queue processing. The search component is written in Java.
Data feeds on the Open Streetmap site.
A PHP application that scrapes some sites and generates RSS feeds for them.
FOSS software which implements a mailing list, not just over email but as a sharable, clonable git repo. Implements nntp, online html archives, and atom feeds. Written in perl. Designed to run on the lower possible common denominator machine. Uses a pull model, which optimizes for casual readers and members while still allowing for serious users.