In the email world, imitation isn’t the highest form of flattery-- forwarding is. There are many things you can do to make your newsletter "forward-worthy." My personal favorite, one that worked wonders on a B2B list, was a simple flash game that cleverly tied the objective of the game to the brand. It had an easy, one-step sign-up field just below the game and then hinted at the cool games to come. There are other ways as well: polls, jokes, quotes and so on.