Type Extensions...

TypeExtensions.cs

 public static class TypeExtensions
  {
      public static bool HasAttribute<TAttribute>(this Type type) where TAttribute : Attribute
      {
          return type.CustomAttributes.Any(a => a.AttributeType == typeof (TAttribute));
      }

      public static IEnumerable<Type> DerivedTypesFrom<T>(this Assembly assembly)
      {
          return assembly.GetTypes().Where(typeof(T).IsAssignableFrom);
      }
  }