Sitting on my hard drive, I've got several Cocoa projects I've written over the years. For most of these, the source code used to be available on the web, but I stopped maintaining the site that hosted them. I'm going to go through those and see which ones may still have practical applications or have code that could be useful for the iPhone and start checking them into Google Code. I periodically raid those projects for code for iPhone projects, so I'm pretty sure there are diamonds left in the mine, so to speak. Well, cubic zirconia, at least.
First up is a set of Cocoa classes for generating bar codes. The code supports almost all two-dimensional barcode symbologies, and is fairly well-tested and stable, having been used in a couple of commercial and in-house applications. I'm not sure if there'd be much value in it, but it shouldn't take much to get it running on the iPhone if anyone needs it. I wonder if you can scan the iPhone's screen with a barcode reader? There might be some cool applications if you can... Does anyone have a barcode scanner and iPhone handy who can test that??
Currently, the code uses categories on NSView and NSImage to do the drawing. It shouldn't take too much effort to make a UIView and UIImage category to do the same thing. The NSBezierPath calls will have to be changed to use CG calls, but I can't imagine it being more than an hour's work (famous last words).
I'll post when I get the Barcode Generator source code uploaded, hopefully will be later today.