public static IEnumerable<Type> GetTypesof<T>()
    {
        return from a in AppDomain.CurrentDomain.GetAssemblies()
               from t in a.GetTypes()
               where t.IsSubclassOf(typeof(T))
               where !t.IsAbstract
               where t.GetConstructor(Type.EmptyTypes) != null
               select t;
    }
    public static IEnumerable<Type> GetTypesofInterface<T>()
    {
        return from a in AppDomain.CurrentDomain.GetAssemblies()
               from t in a.GetTypes()
               where !t.IsAbstract
               where t.GetInterfaces().Contains(typeof(T))
               where t.GetConstructor(Type.EmptyTypes) != null
               select t;
    }