If you are looking for a free tool that provides some artistic design power, Image Tricks may be what you need. Also designed for MAC OS, Image Tricks is really not meant for casual image editing or general image enhancements. Instead, Image Tricks works best for taking digital images and applying and combining effects to generate creative new designs. In fact, Image Tricks is easy enough to use that a new user may well overshoot the creativity level needed for a design. Compared to Seashore, which is a limited-capability image editor, Image Tricks will give you the capability to create brand new designs.
As with every project, you need to know your audience and purpose. With image editing and graphic design, the same concept is true. Knowing the intended use of your image can help you determine what tool to use. GIMP, Seashore, and Image Tricks all offer a different level of editing capabilities. Although GIMP is the only cross-platform tool described, remember that all of these tools are free. When you compare their capabilities and then calculate the cost of commercial tools, you may well come out ahead by using one of these tools.
So, if you are searching for an image editor for personal or work-related use and don’t want to buy one either now or ever, I recommend GIMP. If your needs are smaller and you work with the Mac platform, go with Seashore. If you want to be really creative, try Image Tricks.