I'm working on a Cocoa application for Mac OSX. I'm looking for the best interface design tools.
Currently, I use a combination of Photoshop and Interface Builder. Anybody have any secret weapons up their sleeves?
The best tool out there is Fireworks. I am pretty advanced in most of the CS suite and I must say that for interface design nothing beats Fireworks.
Another vote for Fireworks.
You might also consider Flash CS - which has similar drawing tools and layering approach. It's also a more powerful development environment; faster and has better asset management. Plus, your interface conceptualization potential is near unlimited because you can go as far as animating it if you so desire.
I'd also suggest Fireworks.
I've also recently been doing a lot more with Inkscape these days (RIP Freehand and I'm not a huge AI fan). The interface is quite a bit different than Adobe Illustrator, but once you get the hang of it, it's really a quite amazing application. It also handles export to raster formats much better than AI ever did (meaning that it retains perfect pixel dimensions and seems to have decent compression)
Also take a look at OmniGraffle. It's not aimed directly at UI design, and isn't cheap (but not very expensive either), but it's a very nice general diagramming tool.
There are a lot of useful templates (called "stencils") for OmniGraffle at GraffleTopia, downloadable for free.
This one, for instance: graffletopia.com/stencils/320