As noted earlier, some of the features of Photoshop CS5 are available in the free open source app GIMP. Content-Aware Scale is called Liquid Rescale in GIMP, while Content-Aware Fill is called ReSynthesizer in Gimp. For a few details on these implementations, see More free Photoshop with Content-Aware Scale with the GIMP at Blender 3D Architect.
Even with GIMPshop to reorganize menus, GIMP would take some getting used to, but at least there are options for most platforms.
Today Slashdot and Viz World noted the blog of Portugeuse language website Ultradownloads that shows often decent if different results from both approaches testing several images. There are also YouTube videos of Liquid Rescale (aka seam carving) and Resynthesizer in action in GIMP. Here's an example from Ultradownloads: