The new version of Firefox (Preview Release) has Live Bookmarks: auto-discoverable feeds show up as an RSS button at the button of the window, and subscribing adds a new folder representing that feed to your bookmarks menu.
The new version of Thunderbird also has a built-in feed reader, but it's not clear how this integrates with Firefox's Live Bookmarks, if at all (I haven't tried it yet).
If you're running a version of OS X too old for Safari, then the new version of Camino is highly recommended - it has pretty much caught up with Safari in every respect.
The new beta of Ecto 2 has some very smart features, including WYSIWYG editing.
The newest release of Movable Type has a plugin pack, which includes MT-BlackList, for destroying comment spam.