ThinkUp is a free, open source web application that captures your posts, tweets, replies, retweets, friends, followers and links on social networks like Twitter and Facebook.
With ThinkUp, you can store your social activity in a database that you control, making it easy to search, sort, analyze, publish and display activity from your network. All you need is a web server that can run a PHP application.
Inspired by Yahoo's Pipes, DERI Web Data Pipes implement a generalization which can also deal with formats such as RDF (RDFa), Microformats and generic XML. It is OSS DERI Pipes provides a rich web GUI where pipes can be graphically edited, debugged and invoked. The execution engine is also available as a standalone JAR, which is ideal for embedded use. DERI Pipes, in general, produce as an output streams of data (e.g. XML, RDF,JSON) that can be used by applications. However, when invoked by a normal browser, they will provide a end user GUI for the user to enter parameter values and browse the results
By filtering your results by popularity, you'll be able to pare down a bunch of results that are presumably all relevant into the top sites on your topic, or some surprising ones you might not have heard of.
Love Digg's RSS feed but don't have time to keep up with it all? Disstill is like your regular Digg RSS feed but filters out stories below the minimum diggs that you set.
"Kosmix will give you an 'aspect,' but it's attached to an information source. In our case, all the aspects might be just Web search results, but we'd organize them differently."
What is that all about? It is a service that helps you monitor web sites that do not publish feeds. It will check any web page for updates and deliver them to your favorite RSS aggregator.
PostRank claims to measure social engagement, including blog posts responding to someone else, bookmarking an article, leaving a comment on a blog, or clicking a link to read a news item.