Greader will preserve its own history of a feed, including deleted items and feeds that go down, given someone on the Internet was accessing it, Google caches it.

It means when a website is taken offline, if you are subscribed to, say, a content RSS feed through them, you can still browse the history and content.

I just switched to Akregator, which will locally cache feeds (and you can configure it to do so permanantly) but it is a local copy. You can host your feeds via a feed host through it, so I imagine what I'm going to do is run Akregator off my server box, archive my feeds, and access it from my servers ip.

You can get an RSS file (well, Atom) for any feed that includes all posts going back to whenever google reader started following it. Normally if you get the RSS from the originating site it'll only have the latest 20 or so posts, and there isn't a standardized way to get the history.