While in Windows I was quite used to run Paint.NET (a very useful and free photo editing tool, available at http://www.getpaint.net/) the same quality in a simple Open Source tool is not available for Mac OSX.
I’ve tested GIMP but I do not like it and, above all, the time required to start every time because it need the X server to run is too much for occasional usage, I’ve also tested Seashore but I do not like it, so I’ve decided to purchase a commercial software, and the winner is:
It was quite some time I’ve seen a program polished and finished as that, a truly work of love from a group of passionate and competent developers.
I really do not have anything to say, Pixelmator it’s the best program I’ve found for Mac to edit photo, because it’s fast, it works, it’s seamlessy integrated in every aspect of the Mac OSX operating system and it values much, much more than the very affordable price required to buy it (thanks also to the very favorable euro/dollar exchange rate). Highly recommended, without any doubt.