The code below is a bare bone Layout.Master master page for MojoPortal. I found that the default ones all still had some dependencies on MojoPortal. Since I'm trying to develop most of my features outside the portal (quicker build times), I needed to have something without dependencies that would still help me get something approximating the MojoPortal environment.
<%@ Master Language="C#" AutoEventWireup="true" CodeBehind="~/App_MasterPages/layout.Master.cs" %>
<!DOCTYPE html>
<html>
<head id="Head1" runat="server"><title></title>
</head>
<body>
<form id="frmMain" runat="server">
<asp:ScriptManager ID="ScriptManager1" EnablePageMethods="true" runat="server" />
<div id="wrapwebsite">
<asp:contentplaceholder ID="pageEditContent" runat="server" Visible="false"></asp:contentplaceholder>
<div class="wrapcenter">
<asp:Panel id="divCenter" runat="server" visible="true" cssclass="center-nomargins" SkinID="pnlPlain">
<asp:ContentPlaceHolder ID="mainContent" runat="server"></asp:ContentPlaceHolder>
</asp:Panel>
<asp:Panel id="divLeft" runat="server" cssclass="leftside" visible="True" SkinID="pnlPlain">
<asp:contentplaceholder ID="leftContent" runat="server"></asp:contentplaceholder>
</asp:Panel>
<asp:Panel id="divRight" runat="server" visible="true" cssclass="rightside" SkinID="pnlPlain">
<asp:contentplaceholder ID="rightContent" runat="server"></asp:contentplaceholder>
</asp:Panel>
</div>
</div>
</form>
</body>
</html>