Database access and what options are available. Creating documentation / help for applications. Recommended software for designing beautiful icons for applications (as those traditionally found in every app). Creating custom binary data files as well as text files. Developings games (OpenGL, other options). Interoperability with Windows only data like Access files, executables. Internet access, URL requests, fetching data from REST resources. Manipulation of basic OSX UI devices like the Dock, Menu (status panel in the top), KeyChain, iSight, etc. Running applications in the background (does that even make sense?) Interoperability between Cocoa applications written in Objective-C, Ruby, etc. Packaging and distributing the application Where?