I think I've read it in Carolyn Snyder book, or Todd Zaki Warfel, that most common method of prototyping user interfaces is paper prototyping (according to some survey). Do you think it's still true? Do you paper prototype every of yours projects? How do you deliver your design to client or developers?
Personally I don't have constant workflow. Some projects starts with whiteboard, some with paper. Usually I continue my work in wireframing app creating documentation that communicate the design properly.
I've created uxpin.com system that is able to convert paper prototypes into digital wireframes. You can try it yourself. More details and video demo available here.