Magento 1.7 – How to Change Product Button URL on Home Page

After struggling a bit here is the solution I found. I let my observer execute after the one in Mage_Catalog and decided to re-create the menu entirely.
The main idea is to get all the existing menu items put them in a temporary array, remove them from the menu then add my links between the existing items and in the end add all items to the menu again. Something like this:

public function addItemsToTopmenuItems($observer){
    //get the menu object -Type Varien_Data_Tree_Node
    $menu = $observer->getMenu();
    //get the tree object in the menu -type Varien_Data_Tree
    $tree = $menu->getTree();
    //get current page handler
    $action = Mage::app()->getFrontController()->getAction()->getFullActionName();
    $brandNodeId = 'category-node-brand';
    //set the node id, label and url
    $data = array(
        'name' => Mage::helper('catalog')->__('Brands'),
        'id' => $brandNodeId,
        'url' => Mage::getUrl('brands'),
        'is_active' => ($action == 'brands')
    );
    //create a node object
    $brandNode = new Varien_Data_Tree_Node($data, 'id', $tree, $menu);
    //temporary array with nodes
    $menuItems = array();
    //my first menu item
    $menuItems[] = $brandNode;
    //loop through existing menu items, add them to the array and remove them from the    menu
    foreach ($menu->getChildren() as $child){
        //add the item to the temp array
        $menuItems[] = $child;
        //remove item from the menu
        $menu->removeChild($child);
        //I need to add a new menu item after the category with id 6
        //don't worry the id is not hard coded. it comes from a config setting
        //I just added 6 here to make it easier to read
        if ($child->getId() == 'category-node-6'){
            //create a new node as $brandNode called $newNode
            ...
            //add the node to my temp array
            $menuItems[] = $newNode;
        }
    }
    //add other nodes at the end of my temp array
    ...
    //recreate the menu in the order I need
    foreach ($menuItems as $child){
        $menu->addChild($child);
    }
}

This seams to solve my problem,but I'm hoping for a more elegant method of doing it.

There is an explanation on how you can add menu items in the top menu in this question.
You can use the event page_block_html_topmenu_gethtml_before to add menu items to the top menu.
Your observer can look something like this:

public function addItemsToTopmenuItems($observer){
    //get the menu object: //Type Varien_Data_Tree_Node
    $menu = $observer->getMenu();
    //get the tree object in the menu //type Varien_Data_Tree
    $tree = $menu->getTree();
    //get current page handler
    $action = Mage::app()->getFrontController()->getAction()->getFullActionName();
    $colorNodeId = 'color';
    //set the node id, label and url
    $data = array(
        'name' => Mage::helper('catalog')->__('By Color'),
        'id' => $colorNodeId,
        'url' => '#', // no url because there is no page for color
    );
    //create a node object
    $colorNode = new Varien_Data_Tree_Node($data, 'id', $tree, $menu);

    //now create a node for each available color
    $colors = Mage::getModel('eav/config')->getAttribute('catalog_product', 'color')->getSource()->getAllOptions();
    foreach ($colors as $color) {
         $nodeId = 'color-'.$color['value'];
         $data = array(
            'name' => $color['label'], // color label here
            'id' => $nodeId,
            'url' => Mage::getUrl('catalogsearch/advanced/result', array('_query'=>'color='.$color['value'])), // use the advanced search url with a selected color to avoid creating a separate page.
         );
         $node = new Varien_Data_Tree_Node($data, 'id', $tree, $colorNode);
         $colorNode->addChild($node); //add node as submenu for the main color item
    }
    //add the color main node to the menu
    $menu->addChild($colorNode);
    return $this;
}

I haven't tested the code so you might get some errors, but the idea is the right one. Trust me :).