I like GIMP (Portable). But it is an advanced image editor, and need some times to load the application. Thus, it is not a good idea to run the GIMP for doing tiny works. So, I am looking some other image editor, free and cross-platform (better if open source).
One of the popular image editors is Paint.NET. I tried it, it is nice and lighter than GIMP. But it depends on .NET Framework. I don’t like .NET Framework because it is “heavy” (required a lot of disk space). Thus, I want to find alternative.
Then, I found HeliosPaint. Nice, it is depends on JRE (which is much lighter than .NET). No installation need. Besides, it is cross-platform, for Linux, Mac OS X. (But I haven’t try it to do some serious work.)