RIA Mockup software
If you develop RIA's and are looking for a great tool to quickly create a GUI mockup, look no further than Balsamiq Mockups. I am constantly looking for easy ways to bang out a quick application mockup so I can show it to clients and stakeholders. Typically I default to Powerpoint or Visio, both of which do not offer the variety of controls I need to properly illustrate what the GUI will look like. Thankfully I will no longer have that problem.
Balsamiq Mockups is a super simple tool for creating great looking GUI mockups. The best part for me, as a Flex developer, is that it is a Flex and AIR application. It has most if not all of the "out of the box" components available in Flex Builder, so there is no need to waste time and effort drawing controls. You can simply drag them onto the stage and use them. Clicking on an item allows to change it's properties and items can be moved around, grouped and layered, just like in Visio. There are keyboard shortcuts for copying, pasting, deleting, etc. You can easily modify the data displayed in any control by clicking and typing, even create hierarchies in a Tree control.
Here's a quick demo on using the app.
When resizing a component the size is displayed on screen, which is super helpful. 
To get an idea of what you can do with Mockups, check out the samples, awesome. The rough pencil drawn styling of the components is perfect, no one will accidently assume it's a finished product when you show them the mockups.
They have gotten some good press on Read Write Web and Web Worker Daily.
Giacomo, awesome job, can't wait to see what else you have in the works. Seeing applications like this, done with Flex and AIR just fuels my fire more for continuing down the RIA development path.
If you are an RIA developer, give this tool a look, it's well worth your time.
