var myExplorer = function() {
    var options;
  
    var init = function(settings) {
        var config = {
            $wrapper : $('#explorerCategories'),
            $contentHolder : $j('#categoryContent'),
            loadingImg : '<img src="../images/standard/misc/ajax_loader.gif" alt="loading" class="loading" />'
        }
        // provide for custom configuration via init()
        options = $.extend(config, settings);
        

        // some more code...
    };

    var createExpanderLink = function() {
        // more code
    };

    var anotherMethod = function() {
        // etc
    };

    // Public API 
    // return the functions you want to use outside of the current instance
    return {
        init : init,
        createExpanderLink : createExpanderLink,
        anotherMethod : anotherMethod
    }
}
var firstExplorer = new myExplorer();
var secondExplorer = new myExplorer();
// etc