Edit in JSFiddle

//default dating requirements 
var minAge = 21;
var maxAge = 37;
var reqStatus = "Single";
var reqGender = "F";

//config
var d = new Date();
var year = d.getFullYear();
var cMinYear = year - minAge;
var cMaxYear = year - maxAge;
var cStatus = reqStatus;
var cGender = reqGender;    
    
//generate template of students
var tmplStudent = "<div class='listItemDiv'><div style='float:left;'>${FName} ${LName}</div> <div style='float:right;'>${$item.classAverage()}</div><div style='clear:both;'></div></div>";
$.template( "studentTemplate", tmplStudent );   

//generate map
var map = new GMap2(document.getElementById('map')); 
map.setCenter(new GLatLng(0,0),0);
var bounds = new GLatLngBounds();
var overlays = [];

//eligable logic    
    var dateable = function(student){
        var y2k = "";
        var dob = new Date();
        var dobYear = new Date();
        y2k = student["DOB"].substring(0,6) + "19" + student["DOB"].substring(6);
        dob = new Date(y2k);
        dobYear = dob.getFullYear();

        if (student["Gender"] === cGender & 
            student["Status"] === cStatus & 
            dobYear <= cMinYear & 
            dobYear >= cMaxYear){
                return true;
        }else{
                return false;
        }
    };





    // add students to list and map
    var addToList = function(student, classAverage){
        $.tmpl("studentTemplate", student,{
            classAverage: function() { 
                return classAverage;
            } 
        }).appendTo( "#studentInfo" );   
        
        var lat = parseFloat(student["Lat"]);
        var lng = parseFloat(student["Lon"]);
        
        var point = new GLatLng(lat, lng); 
        marker = new GMarker(point); 
        map.addOverlay(marker);
        overlays.push(marker);
        bounds.extend(point);
    }; 

//find dateable students and get their quiz average
// reset map and list each time
var runFilter = function(){   
    deleteOverlays();  
    $("#studentInfo").remove();  
    $("body").append("<div id='studentInfo'><div style='float:left;'><b>Student Name</b></div> <div style='float:right;'><b>Quiz Average</b></div><div style='clear:both;'></div></div>");  
    $.each(students, function(index,student){
        if (dateable(student)){
            // add up quiz scores
            var classScore = 0;
            var quizNumber = 0;
            $.each(student["Quizzes"], function(index,value){
                classScore += value;
                quizNumber++;
            });
            // add them to the list with their quiz average
            addToList(student, classScore/quizNumber);
        }
    });
    map.setZoom(map.getBoundsZoomLevel(bounds));
    map.setCenter(bounds.getCenter());  
};

// get initial filter
runFilter();

// select gender function
$("#gender").change(function(){

    cGender = $("#gender").val();
                runFilter();
});

//slider function
    $(function() {
        $( "#slider-range" ).slider({
            range: true,
            min: 18,
            max: 60,
            values: [ 21, 37 ],
            slide: function( event, ui ) {
                $( "#amount" ).val(ui.values[ 0 ] + " - " + ui.values[ 1 ] );
                cMinYear = year - ui.values[ 0 ];
                cMaxYear = year - ui.values[ 1 ];

                runFilter();

            
            }
        });
        $( "#amount" ).val($( "#slider-range" ).slider( "values", 0 ) + " - " + $( "#slider-range" ).slider( "values", 1 ) );
    });



// Hide all markers in the array
function deleteOverlays() {
  if (overlays) {
    console.log(overlays);
      for (i in overlays) {
      overlays[i].remove();
    }
    overlays.length = 0;
  }
}

<h1>Classroom Date Finder</h1>
<label for="amount">Eligable
<select id="gender">
    <option value="F">Woman</option>
    <option value="M">Men</option>
</select>
    within an age range of:</label>
    <input type="text" id="amount" style="border:0; color:#f6931f; font-weight:bold;" />

<div id="slider-range"></div>
<div id="map"></div>

<script src="http://maps.google.com/maps?file=api&amp;v=2&amp;sensor=false&amp;key=ABQIAAAAA9pf7MF_DaLd5gJGHkgHWBSgRyJfKxvUsUDuKDID09Cb5D0_ORRS6PirPPO_m7H3rUopPQTIioauDQ" type="text/javascript"></script>

body{font-family:verdana; font-size:12px; color:#666;}
h1{font-size:20px;}
#map { width:500px; height:200px; font-weight:none;}
.listItemDiv{width:500px; height:15px; border-bottom:solid 1px #eee;}