MVC
Web forms
Web forms Tutorials

AjaxCheckboxList

It can be declared using the AjaxCheckboxList or AjaxCheckboxListFor helper like this:
@Html.Awe().AjaxCheckboxListFor(o => o.Meals) 
@Html.Awe().AjaxCheckboxList("Categories") 
It requires a controller to get it's data from, this controller must have an action GetItems which will receive a "v" parameter with the current value, example:
    public class CategoriesAjaxCheckboxListController : Controller
    {
        public ActionResult GetItems(int[] v)
        {
            v = v ?? new int[] { };
            return Json(Db.Categories.Select(o => new SelectableItem(o.Id, o.Name, v.Contains(o.Id))));
        }
    }