If you're serious about having decent tool for mocking up websites, I'd highly recommend the latest OmniGraffle Pro, and the Konigi stencil set: http://konigi.c

If you're serious about having decent tool for mocking up websites, I'd highly recommend the latest OmniGraffle Pro, and the Konigi stencil set: http://konigi.com/tools/omnigraffle-wireframe-stencils http://konigi.com/tools/omnigraffle-wireframe-stencils It's expensive, but wasted time is also expensive. As soon as you run into the limitations of using Flash for mocking up your app within mockflow, you'll end up having to redo a lot of things which all takes time.