ForeUI is a handy UI prototyping tool. It can rapidly create skinnable and
clickable UI prototype for your website or software, and run the interactive
simulation in your web browser.

ForeUI provides a set of predefined elements for creating mockup, you can drag
them into the editing area and tweak them. You can also create your own elements
and libraries.

ForeUI makes prototype skinnable, by changing the UI theme, all elements in
the prototype will change their look. Currently ForeUI provides four UI themes
for prototyping, including Hand Drawing, Wireframe, Windows XP and Mac OS X
themes. These UI themes cover the high, middle and low fidelity degrees, you
can switch the UI themes at anytime, thus the fidelity of wireframe will be
switched as well. The figures below is the same mockup rendered with different
UI themes.

   
 
   
  

You can define the prototype behavior by creating the flow chart for handling
specific events, it will work as you expected during the simulation.

You can click the "Run Simulation" button to run the prototype in
your web browser. All defined behavior will be converted to JavaScript and work
in the browser.

ForeUI works on Windows, Mac OS X, Linux and Solaris. You can choose the tool
look and feel if you'd like. Here are some screen shots for ForeUI with various
look and feel.



ForeUI with the default EaSynth look and feel



ForeUI with Windows XP native look and feel



ForeUI with Mac OS X native look and feel

http://www.foreui.com/