The Arduino IDE is great and provides plug-and-play and instant gratification but, sometimes, complex sketches require a more powerful IDE.
I've developed embedXcode, a template for Xcode 4 and Xcode 5.
Xcode is the free IDE for Mac OS X and provides many niceties such as: syntax colouring, line numbering, function highlighting, code-sense, template with parameters for a function, check-as-you-type, click-to-error, tool-tip texts, object browser, self documentation, git repository management, code snippets, bookmarks, debugging, ...
embedXcode supports Arduino 1.0 and 1.5 (beta) repositories.
• New! Release 107 runs on Xcode 5. The user manual is available as an e-book.
• New! Release 117 adds debugging (link) for boards with built-in debugger.
And the main benefit is faster development.
embedXcode relies on the IDEs of the boards for an easy installation. The set of makefiles can be used with other IDEs. I use Xcode because I own a MacBook, but I tested the set of makefiles successfully with NetBeans.
As at today, Arduino 1.0 and 1.5 (beta) are supported, as well as 6 other Processing-based Wiring-derived Arduino-like IDEs: chipKIT MPIDE, Digispark, LaunchPad MSP430, FRAM and Stellaris, Maple, Teensy 3 and Wiring.
The dedicated website includes
Check the thread Arduino on Xcode Project — Official Thread on the Arduino forum.