Lots here on epigenetics from the Genetic Science Learning Centre, includes videos, information, interactives etc.
Straightforward introduction to epigenetics in the form of diagrams with explanation from Scientific American. A good place to start.
Interesting article on epigenetics from Discover Science magazine.
Part of the Genetic Science Learning Centre epigenetics pages, example of epigenetics in rats explained with an interactive animation (you are mummy rat and investigate the effect of licking baby rats on gene expression!)
Article from The Scientist on plant epigenetics and inheritance of DNA methylation. Interesting background reading, goes into more detail than you need.
A pdf file topic chapter on regulation of gene expression, includes the lac operon and epigenetics.