My6Sense
Despite the famous movie, balance is generally considered to be the sixth sense, not talking to dead people. (Some argue for ESP or proprioception.)
Balance is a great metaphor for what My6Sense is designed to do. It is a mobile filtering application — running on iPhone in the current beta — that takes all sorts of streams, and over time learns your preferences, filtering the information that is most timely and relevant.

my6sense_iphone_2, originally uploaded by Stowe Boyd.
The app supports sharing something that comes along on various services, and integrates commenting . For example, if I see something a blog post I can (in general), respond by sending a comment to the blog. (In the case of my blog where I am using Disqus comments, that integration doesn’t work yet, but they are planning to support it.) So you can respond to Tweets, or add comments to Friendfeed, and so on.
The adaptive learning aspect is most interesting to me. At different times I may be more interested in certain sorts of streams, topics, or people. My6Sense will be learning more and more about my pattern of use, and get better at selecting what I want to see, right now, helping me to balance my time with my interests.
[disclosure: I am a member of the My6Sense advisory board.]