MockFlow vs Moqups
MockFlow WireframePro is a web-based tool to design and collaborate user interface blueprints for websites and apps. Its helps to visualize the website's interface, navigation and structure in short time. With web and desktop clients, you can design seamlessly from anywhere & even with No net-connection. Organize pages with sitemaps and define links to present a clickable prototype.
Moqups is a nifty HTML5 App used to create wireframes, mockups or UI concepts, prototypes depending on how you like to call them.