HSLayers.Control.ScaleSwitcher indicates current map scale and user can also change map scale directly.
var switcher = new HSLayers.Control.ScaleSwitcher({
div: this.mapViewer.mapPanel.scaleSwitcherContainer.container.dom
});
map.addControl(switcher);
The switcher will render combo box with OpenLayers.Map.scales or scales derived from OpenLayers.Map.resolutions (which are actually calculated based on attributes from OpenLayers.Map.baseLayer).