An iOS version of my Gloss Gradient drawing code
Two persistent stores with one NSPersistentStoreCoordinator
A full set of "single line Core Data fetch" methods
Pulling data from an RSS feed
Getting the GPS location
Caching data in the Application Support directory
Function to create a two point CGGradientRef from two UIColors
An example of using a category as an Adapter interface
Scrolling a text field that isn't in a table
A Core Data Postcode database
A flexible, reusable controller/table/cell structure
A CheckmarkCell that self-manages radio button style selection
Forward geocoding using Google's Maps API

Mac OS X contains a number of 'secret' debugging facilities, including environment variables, preferences, routines callable from GDB, and so on. This technotes describes these facilities. If you're developing for Mac OS X, you should look through this list to see if you're missing out on something that will make your life easier.