A jQuery Form Wizard is a jQuery plugin that assists with the creation of forms with some sort of form flow (without refreshing your page). For example, if you had a large form for entering user data, you could use a form wizard to divide it into a series of related steps. This has the advantage of not overwhelming users with a really long form and also giving them some indication of their progress as they enter their information.
And finally, at number six we have jQuery.wizard. This is an asynchronous form wizard that supports branching—something requested by people in the comments.