Recently I needed to traverse the visual tree of a Silverlight dependancy object (UI element) in order to find a child object with the type I was looking for. As I didn't know how far nested the child would be, I wrote a recursive helper function which will scan all child elements looking for the first instance it finds. I then extended this functionality with a overload allowing to specify the name of the object I was looking for. I thought it might be useful elsewhere, so here it is:
private T FindControlByType<T>(DependencyObject container) where T : DependencyObject
{
    return FindControlByType<T>(container, null);
}

private T FindControlByType<T>(DependencyObject container, string name) where T : DependencyObject
{
    T foundControl = null;

    //for each child object in the container
    for (int i = 0; i < VisualTreeHelper.GetChildrenCount(container); i++)
    {
        //is the object of the type we are looking for?
        if (VisualTreeHelper.GetChild(container, i) is T && (VisualTreeHelper.GetChild(container, i).GetValue(FrameworkElement.NameProperty).Equals(name) || name == null))
        {
            foundControl = (T)VisualTreeHelper.GetChild(container, i);
            break;
        }
        //if not, does it have children?
        else if (VisualTreeHelper.GetChildrenCount(VisualTreeHelper.GetChild(container, i)) > 0)
        {
            //recursively look at its children
            foundControl = FindControlByType<T>(VisualTreeHelper.GetChild(container, i), name);
            if (foundControl != null)
                break;
        }
    }

    return foundControl;
}
You can tweak the code to accept more parameters if you need more comparisons to match your object.