Tax You for Doing Nothing

Professor Jacobson puts it simply (with regard to taxing provisions in the proposed health care reform bill):

What a bizarre concept is a tax to enforce a health care mandate. If you buy a computer at a store, you expect to pay a sales tax; but do you expect to pay the tax for not buying a computer? If you earn income at a job, you expect to pay taxes on the income; but do you expect to pay taxes for not working?

I wonder how many other taxes and fees are already levied against US citizens for not doing things which are revenue generating?