XML: (Facts.xml)

<?xml version="1.0" encoding="utf-8" ?>
<facts>
  <fact>
    The numbers '172' can be found on the back of the U.S. $5 dollar
    bill in the bushes at the base of the Lincoln Memorial.
  </fact>
  <fact>
    President Kennedy was the fastest random speaker in the world
    with upwards of 350 words per minute.
  </fact>
  <fact>
    In the average lifetime, a person will walk the equivalent of 5
    times around the equator.
  </fact>
    .
    .
    .
</facts>

Code: (RandomFact.ascx.cs)

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Caching;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Xml;
using System.IO;
using System.ComponentModel;
using System.Drawing.Design;
 
public partial class _controls_RandomFact : System.Web.UI.UserControl
{
    private string _xmlDataSource;
    [UrlProperty()]
    public string XMLDataSource
    {
        get { return _xmlDataSource; }
        set { _xmlDataSource = value; }
    }
    protected void Page_Load(object sender, EventArgs e)
    {
        litFact.Text = getRandomFact();
    }
    private string getRandomFact()
    {
        Random rndIndex = new Random();
        XmlDocument xmlDocFacts = new XmlDocument();
        string strFact = string.Empty;
 
        try
        {
            if (Cache["xmlDocFacts"] != null)
            {
                xmlDocFacts = (XmlDocument)Cache["xmlDocFacts"];
            }
            else
            {
                xmlDocFacts.Load(Server.MapPath(XMLDataSource));
                Cache.Insert("xmlDocFacts", xmlDocFacts, new CacheDependency(Server.MapPath(XMLDataSource)));
            }
 
            XmlNodeList xmlNodesMessage = xmlDocFacts.SelectNodes("//fact");
            int rnd = rndIndex.Next(0, xmlNodesMessage.Count);
            strFact = Server.HtmlEncode(xmlNodesMessage[rnd].InnerText);
        }
        catch (Exception ex)
        {
            strFact = string.Format("<b>Error:</b> {0}", ex.Message);
        }
 
        return strFact;
    }
}

Usage: (Default.aspx)