Adobe Fireworks
I’m officially adopting Fireworks over Photoshop for website prototyping because of one particular feature. Like Flash, with Fireworks you can create a ‘symbol’, let’s say a thumbnail border, and place multiple instances of that thumbnail border on a page. If later I decide to change the color of the border, I can simply edit the master symbol and the change would filter down to all instances. Oh, and you can auto align objects. I’m going guide-free!
Aside, the UI is a little junky, but excusable.
Zach, It’s buggy as hell on OSX. But coming from an interactive designer who has used this tool daily for over 5 years now, it’s amazing for what it is. I can’t imagine having to design a site in Photoshop.
Source: zachklein