Lately most of the projects I've been involved with have used Agile methods to help our development teams keep up with the changing demands of our customers. In the present economic climate we are using these methods to achieve more with less. I'm currently working with Rally Software to help provide a framework for management our projects and simplify the art of project managing Agile development.
When we are working with our customers we sometimes find it useful to discuss and evaluate business requirements in the form of user stories on paper, rather than relying on everyone staring at a computer screen.
Below is an example of a user story card we developed for this purpose. The card can easily be printed from the attached PDF file onto 8.5x11 card stock. Each card is designed to be ½ page in height. I hope that it may help as you are defining your iterations:
(User Story Card front)
(User Story Card back)
HitachiConsultingStoryCardV2.pdf (304.62 kb)
If you need help writing user stories you can find more information on the Wikipedia here: User Stories
If you are looking for additional resource to help with your Agile projects you might want to check out the Agile Commons.