Congratulations to Flying Meat Inc. on their release of Acorn 3.0.
Acorn is my favourite image editor on any platform. It’s small, very capable, has an elegant UI, and is affordable. In fact, 3.0 is on sale for $30 at the moment. If $30 is too much for you, download the trial version. When it expires, reverts to a still-excellent free mode.
Honestly, even with Adobe Photoshop CS5 available to me, I still use Acorn for all but the biggest, least-pleasant jobs.