Balsamiq Collaborative Software Mockup Tool

[Nate Angell]

Thought those of us who mock up UX and develop applications might be  
interested in this new tool that enables quick, collaborative UX  
mockups. It integrates with Confluence & Jira, and is based on Adobe  
AIR.
http://www.balsamiq.com/

Unfortunately, it's a $79, but you can try it out for free to see if  
you think the price is worth it...looks pretty nifty.

I learned about it from the review here:
http://www.readwriteweb.com/archives/balsamiq_mockup_creator_is_on_fire.php