I get reminded of this service every 6 months or so. I always take a class or two myself and encourage friends and family members to do so as well.
Essentially HP has about 200 classes that are simply excellent and free. Some are text based, in that you read through a few pages of content. Others are videos you watch, and others are classes that expect you to learn something. All the classes are viewable at the HP Learning Center.
This is the featured lesson and took me about 10 minutes to go through.
Many of the lessons follow this format and are split into a few topics, within the lesson itself. Very easy to figure out and navigate.

This lesson on handling e-mail is in the form of a video that explains the concept.
These are a great tool. If you don't find them useful, I encourage you get them over to friends and family to see if they can make use of them. I'd love to hear what you think of them.
I worked for HP.