Is there an accordion-style menu module?
DHTML Menu is great and it should work for what you need. I haven't used the 7.x version yet but they have a stable release. Here is an excerpt about it from the module's project page:

... uses Javascript to reduce the number of page loads when using nested menus; this is particularly useful with Drupal's administration system.
Ordinarily in Drupal, in order to see the sub-items in a menu, you need to click the link of this item and wait for a full page load. After enabling DHTML Menu, clicking a menu link once will expand it to reveal its sub-items without reloading the page. A double-click on the item will load the page normally. Additionally, a cookie stores which menus are open and which are closed, so that the state of the menus remain consistent as you navigate around the site.