Files needed to do inline ads/reviews/whatever

IListType.cs

namespace ScottIsAFool.Windows.Core.ViewModel
{
    public interface IListType
    {
        ListType ListType { get; }
    }
}

ItemTypeDataTemplateSelector.cs

using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using ScottIsAFool.Windows.Core.ViewModel;

namespace ScottIsAFool.Windows.Data
{
    public class ItemTypeDataTemplateSelector : DataTemplateSelector
    {
        public DataTemplate NormalTemplate { get; set; }
        public DataTemplate AdTemplate { get; set; }
        public DataTemplate ReviewTemplate { get; set; }

        protected override DataTemplate SelectTemplateCore(object item)
        {
            var listType = item as IListType;
            if (listType == null)
            {
                return base.SelectTemplateCore(item);
            }

            switch (listType.ListType)
            {
                case ListType.Normal:
                    return NormalTemplate;
                case ListType.Ad:
                    return AdTemplate;
                case ListType.Review:
                    return ReviewTemplate;
                default:
                    return base.SelectTemplateCore(item);
            }
        }
    }
}

ListType.cs

namespace ScottIsAFool.Windows.Core.ViewModel
{
    public enum ListType
    {
        Normal,
        Review,
        Ad
    }
}

ListTypeExtensions.cs

using System;
using System.Collections.Generic;
using System.Linq;
using ScottIsAFool.Windows.Core.ViewModel;

namespace ScottIsAFool.Windows.Core.Extensions
{
    public static class ListTypeExtensions
    {
        public static List<IListType> AddEveryOften(this IEnumerable<IListType> collectionList, int everyOften, int maxNumberToShow, IListType itemToAdd, int startAt = 0, bool addAsFirstItem = false)
        {
            var list = collectionList.ToList();
            if (list == null || !list.Any())
            {
                return new List<IListType>();
            }

            var itemsAdded = 0;
            var numberOfItemsToAdd = Math.Floor((decimal)list.Count / everyOften);

            for (var i = 0; i < numberOfItemsToAdd; i++)
            {
                var multiplyValue = addAsFirstItem && startAt > 0 ? i : i + 1;
                var addAt = addAsFirstItem && i == 0 ? startAt : (multiplyValue * everyOften) + startAt;
                if (addAt > list.Count)
                {
                    break;
                }

                list.Insert(addAt, itemToAdd);

                itemsAdded++;
                if (itemsAdded == maxNumberToShow)
                {
                    break;
                }
            }

            return list;
        }
    }
}