As mentioned above, crafts and learning something new are good. If you are already good at something, teaching is good. It doesn't have to be in person. You can participate in an established site, or start your own. Write a book, column, comic strip, etc. If there is any charity or cause that you are interested in, there are ways to participate from home. This site is one of them. If you have any political interests, you can participate in the national discussion. Write your representatives, company heads, organizations. It gets frustrating when there's so much you can't do, but there are plenty of ways to be productive. www.blogger.com is also an easy way to start a blog.