A lot of Windows software has Alt-key shortcuts to access items on dropdown menus. For example, you can hold down the Alt key, and then press F and S to save a document (File menu, Save item).
AutoCAD 2010 turns off the menu bar, but today I noticed that Alt sequences still work, but in different areas from menu bars.
Press the Alt key, and tooltips appear near buttons in the Quick Access toolbar and tabs in the ribbon, as shown below:
Press key(s) to access the items, such as 1 for New Drawing and R for the Render tab.
Then AutoCAD displays tooltips with keyboard shortcuts for each item in the tab, such as XR for a button, VS for the droplist, VY for the panel extension, and VM for the options dialog box. (Shown below are the tooltips for the Render tab.)