Techcrunch is pushing Nsyght up as a very promising ones social world curator. So I checked out after reading what seems like a sales leaflet.
Yes it is a pretty useful tool, Nsyght allows you to bring together Twitter, Facebook, digg, Vimeo, Stumbleupon, Flickr, Delicious information, and yes it is fast, like TC mentioned. Add this to include Twitter saved searches and Twitter lists! I think, your social graph or social search is complete, more or less. I am going to check Curated.by, once I get an invite!
You can read TC pitch and the Nsyght.