The Forumzilla project has been around since about May/June of 2004. It is an extention of the Mozilla Thunderbird mail client that allows you to use it as a RSS/XML feedreader.

We've takens some screenshots for you to enjoy.

"Forumzilla 0.5.2. Highlights include a new subscriptions manager for maintaining your feed subscriptions, the option to download stories into any local/POP folder, no need for a separate News & Blogs account, a link for opening stories in your web browser, a fix for the bug that caused Forumzilla to redownload stories after you deleted them, some performance improvements, and a bunch of other bug fixes."

Forumzilla project