PhotoLine is an image editing software compareable to Photoshop Elements but with a lot(!) more and important features like curves and channel mixer that I really missed in Photoshop Elements.
Because Photoshop Elements 2.0, which came with my camera, does not run anymore after my update to Mac OS 10.5, I was looking for an alternative software with similar features. PhotoLine impressed me the most. I have to admit the user interface is not really beautiful and might frighten some Mac users off who are used to use fancy software but once you get used to the ordinary look of PhotoLine and focus on the features, you really have to be amazed. Of course Photoshop CS3 offers even more ( for 1000€ ) but compared to Photoshop Elements, you get a lot more for your money with PhotoLine.
Together with Adobe Lightroom I have some overlapping features now but a very powerful combination of software to edit and organize my photos that leaves no wishes open.
Hm. Reading that text again it sounds like a commercial to me but it really is an impressive software.
The screenshot shows one of the neat filters that are built in called "beautify" with a before/after preview window.

PhotoLine is Shareware and you have to pay 59€ if you want to use it for more than 30 days. Worth every cent and you get a nice PDF manual with more than 300 pages after registering the software.