Linq2ArcObjects contains a LINQ-provider for feature cursors and sets. It allows you to use LINQ-style and lambda syntax for accessing features.
One simple LINQ sample to get all features with an area above a threshold of 3000:
var largeFeatures = from feature in features where (feature.GetValue("SHAPE_Area").ToDouble() > 3000) select feature;
The same with a lambda expression:
var largeFeatures = features.Where(feature => (feature.GetValue("SHAPE_Area").ToDouble() > 3000));
This prototype has also some unit test to show you the usage of the constructs.
The whole documentation you could read in the wiki here.