For the Atlanta Java User Group I have been looking into providing an RSS feed aggregation service for blogs of AJUG members. Since AJUG is running its own server, I wanted to provide a server-based solution. Interestingly, it seems the choices are rather slim when looking for something that is OSS. Pratik mentioned groovyblogs. It looks interesting, got it running very quickly, but I saw one too many stacktraces when clicking through the application. Maybe just bad luck...Once I find the time to dive deeper into Groovy and Grails, I may return to groovyblogs, though. The source code is available here.
Barry Hawkins pointed me to Planet, a Python-based feed aggregator. To see it in action, take a look at http://planet.python.org/. Well, after looking at it, I found Planet Venus its successor. Compared to the original Planet, Planet Venus actually has some documentation (I like documentation!) and a fairly active mailing list. Furthermore, nature.com is using Planet Venus. You can find it at http://planet.nature.com/. There is also blog entry by Sam Ruby that provides a little more background information regarding Planet Venus.
Anyway, the actual installation has been trivial - it is basically just a command line script, that parses RSS feeds, applies a template and than spits out html pages. Thus, adding the script's execution to your crontab is all that is needed to feed your aggregator with new data.