<script type="text/javascript">
    //<![CDATA[
 
    if (GBrowserIsCompatible()) {
      // this variable will collect the html which will eventually be placed in the side_bar
      var side_bar_html = "";
    
      // arrays to hold copies of the markers and html used by the side_bar
      // because the function closure trick doesnt work there
      var gmarkers = [];
      var htmls = [];
      var i = 0;
 
 
      // A function to create the marker and set up the event window
      function createMarker(point,name,html) {
        var marker = new GMarker(point);
        GEvent.addListener(marker, "click", function() {
          marker.openInfoWindowHtml(html);
        });
        // save the info we need to use later for the side_bar
        gmarkers[i] = marker;
        htmls[i] = html;
        // add a line to the side_bar html
        side_bar_html += '<a href="javascript:myclick(' + i + ')">' + name + '</a><br>';
        i++;
        return marker;
      }
 
 
      // This function picks up the click and opens the corresponding info window
      function myclick(i) {
        gmarkers[i].openInfoWindowHtml(htmls[i]);
      }
 
 
      // create the map
      var map = new GMap2(document.getElementById("map"));
      map.addControl(new GLargeMapControl());
      map.addControl(new GMapTypeControl());
      map.setCenter(new GLatLng(53.386719, -1.503507), 8);
 
      var side_bar_html = "";
      
      // === Define the function thats going to process the text file ===
      process_it = function(doc) {
        // === split the document into lines ===
        lines = doc.split("\n");
        for (var i=0; i<lines.length; i++) {
          if (lines[i].length > 1) {
            // === split each line into parts separated by "|" and use the contents ===
            parts = lines[i].split("|");
            var lat = parseFloat(parts[0]);
            var lng = parseFloat(parts[1]);
            var html = parts[2];
            var label = parts[3];
            var point = new GLatLng(lat,lng);
            // create the marker
            var marker = createMarker(point,label,html);
            map.addOverlay(marker);
          }
        }
        // put the assembled side_bar_html contents into the side_bar div
        document.getElementById("side_bar").innerHTML = side_bar_html;
      }          
          
      GDownloadUrl("markers.txt", process_it);
    }
 
    else {
      alert("Sorry, the Google Maps API is not compatible with this browser");
    }
   
 
    //]]>
    </script>

GDownloadUrl("markers.txt?", process_it);

<?php
header("Cache-Control: no-cache, must-revalidate"); // HTTP/1.1
header("Expires: Mon, 26 Jul 1997 05:00:00 GMT"); // Date in the past
?>

:D I'll get downloading that.

Yeah, I've just made a small PHP form where I just enter both co-ordinates, the data for the list on the right, and the data that goes in the marker bubble, and that gets put at the end of the file to extend the list of markers.

51.128217|1.337110|26/01/2008 - 21:49<br /><img style="width:300px; height:202px" src="boat.jpg" />|26/01/2008 - 21:49
50.965761|1.857024|26/01/2008 - 22:09|26/01/2008 - 22:09
51.025710|2.353960|26/01/2008 - 22:30|26/01/2008 - 22:30
50.636200|3.050380|26/01/2008 - 22:59|26/01/2008 - 22:59
50.842330|4.351970|26/01/2008 - 23:13|26/01/2008 - 23:13