In the Installing Add Ons Training Page, most of the recommended Add Ons are listed on a PDF download that my son was unable to load, and there is a separate link to Piciens. Anyway, here are the download links:
Piciens - This gives you cool image and video viewing options. Full Screen, 3D.
Google Global - This allows you to customize your Google searches to filter for location.
Google Notebook - Get a notebook on your bottom toolbar.
SEO Tools - This is for marketing stuff we'll learn about later.
Search Status - Shows website ranks right on your toolbar.
StumbleUpon - Sets up StumbleUpon on your toolbar.
TwitterBar - Sets up a TINY link in your address bar that allows you to post to Twitter directly from your address bar.