Luke H. shows how to write a ray tracer using C# 3 and LINQ in about 400 lines of code.
Ray tracing is a method of rendering 3D images on a two dimensional surface such as a computer screen or a printed page. It usually relies on backtracking a virtual light beam from a pixel on the 2D surface to the first three-dimensional object it strikes. Depending on the texture of the object it strikes, it may continue to backtrack until it reaches a light source.
Luke uses LINQ to simplify code for sorting and filtering collections, as well as a replacement for loops when calculating intersections. Object and collection initializers are demonstrated, though they do not significantly change the code in this example.
The use of lambda expressions instead of subclasses and overrides or explicit delegates is the real winner for increasing clarity and reducing lines of code.
A write-up on the ray tracer and the source code is available on Luke's blog.