It really would be oh so nice to have something that can ingest RSS and Tweets and then apply filters to them while visualizing the logic through a graphical interface. Maybe even some fuzzy machine learning to use in building filters. Some more advanced dupe technology would go a long way. People would be building their own techmemes in no time. You could build ranking systems that award bonus points if something like longform or techmeme mention something.
Maybe im dreaming about a free version of Percolate, which I have heard is really cool.