ASP.Net supports dynamic code generation and compilation. Sometimes, you just need a quick and dirty solution. This is one such solution. It writes out a control script, loads it and then deletes the file.

string dynamicControlUrl = "~/" + System.Guid.NewGuid().ToString() + ".ascx";
string dynamicControlPath = Server.MapPath(dynamicControlUrl);
TextWriter tw = new StreamWriter(dynamicControlPath);
tw.WriteLine("<%@ Control language=\"c#\" %>");
tw.WriteLine("<script runat=\"server\">");
tw.WriteLine(" protected void Page_Load(object s, EventArgs e)");
tw.WriteLine(" {");
tw.WriteLine(" Response.Write(\"Hello World!\");");
tw.WriteLine(" }");
tw.WriteLine("</script>");
tw.Flush();
tw.Close();
Control dynamicControl = Page.LoadControl(dynamicControlUrl);
Page.Controls.AddAt(0, dynamicControl);
dynamicControl = null;
File.Delete(dynamicControlPath);