Electricity is often subsidized (which is sort of a negative tax). Here's what my power company (PG&E) does:
http://pge.com/res/financial_assistance/
Also, there's "baseline" quantity pricing and "over baseline" -- it's more expensive to use more than some vaguely defined 'fair share' ... I get hit by this because I work at home and thus use more than I "should" which I guess is fine, but I also don't drive my car to/from work each day :-)
/jordan