An interesting feed reader. Feedling is a Windows-based RSS reader that sits handily on your desktop. It's a .NET 3.5 WPF app that's been tested on XP, Vista and 7 (both x86 and x64), and should work on 2000 as well. I find it useful, even if no-one else does. It might well work on other architectures, under Mono. I've not tested this at all and it will probably break horribly. Besides, there's probably much better solutions on those architectures anyway.
As an RSS reader, Feedling can read a variety of different formats. Currently, it can cope with RSS 1.0, RSS 2.0, RDF and Atom.
In terms of other features, it's pretty simple at the moment. It can read any number of feeds that you want and then chucks a maximum of 10 items onto your desktop, refreshing every 10 (or so, it's fuzzy) minutes. Clicking on these headlines will open the relevant url in your favourite browser. Various bits and pieces are customizable, such as font, colour, proxy, credentials and refresh interval. Certain other things are not customizable, such as my favourite colour.
The license of this software is Free, you can free download and free use this rss reader software.