Currently in private beta

What S:N can do

• Highlight tweets that interest you
• Quietly hide people's tweets
  • Filter their retweets, baseball chat, or Foursquare checkins
  • Throttle them during certain times or days
• Ignore trending topics, certain hashtags, TV and movie spoilers, or anything you can think of with highly-customizable filters
• Cut out Foursquare or just the tweets about mayorships and badges
• Adjust your "signal level" on the fly — show everything, or only the tweets you want
• Save tweets for later, or save links to Instapaper, Read It Later, or Pinboard

Works well on iPhone, iPad, Android, and most other mobile devices