A dynamic object to wrap WebConfigurationManager.AppSettings to access the settings "prettily". Great in combination with a custom ASP.NET MVC WebViewPage for easy access in views.

MyWebViewPage.cs

public abstract class MyWebViewPage<TModel> : WebViewPage<TModel>
{
    public dynamic Settings
    {
        get { return SettingsHelper.Instance; }
    }
}

public abstract class MyWebViewPage : WebViewPage
{
}

SettingsHelper.cs

public class SettingsHelper : DynamicObject
{
    private static dynamic instance = new SettingsH();
    private static object syncRoot = new object();

    private SettingsHelper() { }

    public static dynamic Instance
    {
        get {
            if (instance == null)
            {
                lock (syncRoot)
                {
                    if (instance == null)
                        instance = new SettingsHelper();
                }
            }

            return instance;
        }
    }

    public override bool TryGetMember(GetMemberBinder binder, out object result)
    {
        if (WebConfigurationManager.AppSettings.AllKeys.Contains(binder.Name))
        {
            result = WebConfigurationManager.AppSettings[binder.Name];
            return true;
        }
        result = null;
        return false;
    }

    public override bool TrySetMember(SetMemberBinder binder, object value)
    {
        var key = binder.Name;

        if (WebConfigurationManager.AppSettings.AllKeys.Contains(key))
            WebConfigurationManager.AppSettings.Set(key, value.ToString());
        else
            WebConfigurationManager.AppSettings.Add(key, value.ToString());
        return true;
    }

    public override string ToString()
    {
        StringWriter message = new StringWriter();
        foreach (var item in WebConfigurationManager.AppSettings.AllKeys)
            message.WriteLine("{0}:\t{1}", item, WebConfigurationManager.AppSettings[item]);
        return message.ToString();
    }
}