A company called Movable Ink offers simple yet powerful apps to jazz up your average email newsletters and encourage customer response. Among their apps is a countdown timer that sets a ticking clock in motion for limited time offers, a live twitter feed plug in, and a map app that shows the customer's location in relation to your business.
They also can automatically test creative with your list allowing you to rollout the one with the highest response rate.
Prices start at free, then there's pay-as-you-go and an unlimited plan.
Check out movableink.com more information.