Linq to Streams - aka SLinq
Oren Novotny - a contributor to i4o, has come out with a new LINQ "flavor" called SLinq.
SLinq allows you to do LINQ operations on live streams of data, notably, things like live stock feeds. SLinq is an important part of the LINQ ecosystem, as it extends it to sources of data that constantly change. Oren does a much better job of explaining the technology than I can do it justice for, so I encourage you to check out the codeplex site and read for yourself.
As an aside, the Linq-to-* space is more proof that innovation is alive and well in .NET land. :)