Anonymous Type of an existing type

I find the .NET anonymous type a bit weak in terms of a few more features:

  1. Can't inherit/implement an existing type
    var x = new : IMyInterface {
       Number = 1,
       Name = "Hi",
  2. Can't add methods
    var x = new {
       Number = 1,
       Name = "Hi",
       Action = delegate(object o){ return true; },

I guess anonymous types are purely for quick throw-away data constructs.  I might just as well write a class directly with all the stuff I wanted.