More aggregators -UPDATE-

Some new RSS/ATOM/... aggregators:

LINUX

Lifeera, abbreviated for Linux Feed Reader, parses RDF/RSS, CDF, Atom 0.2, OPML 1.0 and OCS 0.4 and depends on GTK/GNOME
SnowNews - "text mode RSS newsreader for Linux and Unix"
Syndigator comes in GTK and GTK2 flavour

LINUX, WINDOWS

Really Radical Reader for RSS, or R3R reads RSS, ESF and Atom feeds. This PHP/GTK application comes with Windows and Linux installers. HTTP request headers can be customized

WINDOWS

CROSS-PLATFORM

RSSbot "reports live updates via IRC, IM (Yahoo, AOL/ICQ, MSN), e-mail, etc." PERL/POE based. Via decafbad
RNews requires a web server. Similar to Feed on Feeds, it uses PHP, MySQL and Magpie RSS, but has a different interface
FeedWinder and RSSOwl are JAVA based
zShaped and zFeeder have been known as zvonnews and zvonfeeds - PHP based
Simplog is a weblogging tool that also comes with a RSS/RDF/Atom feed reader. Former MyPHPblog. PHP Atom parser class available
Urchin requires PERL and MySQL. Combines items from multiple sources (feeds) into a new RSS feed. Scriptable, no GUI
Feedo is vaporware so far, but promises to come with a "centralized feed status repository [that] avoids seeing articles read on machine #1 as "unread" on machine #2"
Spycyroll is for the Python afficionado
Pears requires Python and wxPython
TALAggregator uses Python and MySQL to implement multi-user, web-based aggregation

OTHER

Winksite also provides aggregation services for mobile devices
TofuRSSBrowser claims to be a "small and simple RSS browser for OS X"
feed-me.info is another online aggregating service
RSSmail lets you access the contents of your IMAP inbox via RSS
fetchRSS "polls Weblogs (RSS feeds) and emails the updates, one message per updated entry" - via vowe
HEP Message Server is Abe Fettig's idea of a multi messaging system gateway. Check his weblog for updates
Amphetarate tries to add a reputation system to Amphetadesk

Reminds me that the directory needs a serious overhaul:

hebig.org/blog