The ever-popular Gravity Forms plugin is on a roll with version 1.6 in beta and due out any day, loaded with improvements upon 1.5. If you haven’t heard of Gravity Forms, then you need to check it out right now. The WordPress community absolutely loves this plugin due to how easy it makes building and publishing WordPress forms. If you’re already using Gravity Forms, check out some of the free add-ons available in the plugin repository for extending it even further.
Gravity Forms Directory & Addons