It would be trivial to make one based on the hello world examples. Just chop out the UpdatePanel and add the adrotator the same as it is added in layout.master.
You can download the hello world examples and modify, or just paste this into a text file and name it yourcustomname.ascx and install it as indicated in the hellow world article.
Hope it helps,
Joe
Example is from here down:
<%@ Page Language="C#" ClassName="MyCustomAdRotatorModule.ascx" Inherits="mojoPortal.Web.SiteModuleControl" %>
<%@ Import Namespace="mojoPortal.Business" %>
<%@ Import Namespace="mojoPortal.Business.WebHelpers" %>
<%@ Import Namespace="mojoPortal.Web.Framework" %>
<%@ Import Namespace="mojoPortal.Web.Controls" %>
<script runat="server">
protected void Page_Load(object sender, EventArgs e)
{
}
</script>
<<mp:AdRotator id="ads1" runat="server" AdvertisementFile="~/App_Data/mojoads.ads" />