It's not cheap by any means but there is of course PhotoShop (which I love) but there is also free programs such as GIMP and Aviary.
They're not "Photo editing" software, but they're great programs that can do good photo editing when you learn their abilities
I am currently using Image Data Lightbox SR that came with my Sony DSLR, Canon MP190 that came with my printer, and Ulead Photo Express. They are all pretty good, but I need to be able to do editing such as removing power lines from photos and I need to be able to put a water mark on some of my photos. Can someone suggest a good editing program that's not too expensive?