Mockingbird - Wireframing on the fly
Mockingbird is an online tool that makes it easy for you to create, link together, preview, and share mockups of your website or application.
Features
All the UI Elements you need
Mockingbird is made for website and webapp wireframing, so it has the elements you use most.
Multiple pages
Mock up as many pages as you need, link them together, and rearrange them with ease.
Fully web-based
Nothing to install or download, and you (and your clients) can access your mockups from anywhere.
Smart text resizing
Resize an object and the text in it will automatically resize, making wireframing faster and life easier.
Clean and clear mockups
Produce results that look clean and professional without being bogged down in unnecessary detail.
Better user experience
Mockingbird has plenty of little touches (like snap-to-grid) meant to make mocking hurt less.
Demo: http://gomockingbird.com/
License: