Graphics package for 3.1

[Ral-Clan]

ImageFX is great (perhaps the best) but not free.

The Amiga software with the closest interface to Photoshop/GIMP is Art Effect.  But again it's not free:
http://www.amigaos.net/software/97/arteffect

As for free software:

You might want to PerfectPaint.  It's the only one I can think of that's absolutely free and advanced enough to do photo-editing (although it's interface is different than Photoshop).
PerfectPaint 2.93 was the latest version.  For some reason it's hard to find now, as the original website is long gone, but it's freeware. I don't read German, but I think you can download it here:
http://www.amiforce.de/perfectpaint/perfectpaint.php

Personal Paint has also been released for free by Cloanto, I think, but it's more like DPaint in the way it works.  Very nice, but maybe not the best for photo-editing.

TVPaint was also released a while ago to the public domain....but again it's got an unusual interface and is not really a photo-editing package (although it could probably do it well). It was originally designed to create TV graphics.

[Ral-Clan]

Yes, there's AdPro (or Art Department Professional).  Again, not freeware.

It might not be great for photo-editing though, as the interface was on a different screen than the render display screen.  What AdPro excelled at was image processing (i.e. applying filters), conversion, and automated batch processing of dozens or hundred (or thousands) of images.