New plugin (in development) for SketchUp to add integrated lighting into the SketchUp interface. http://www.light-up.co.uk The software is not available right now, but you can follow along on this site.
Photoshop Express is a new variation on Photoshop, for 'any' user, without cost. Sing up at http://www.adobe.com/products/photoshopexpress and see what happens. We have been using Photoshop Elements in our classroom, instead of the full version, since it does enough for our students and the educational price was reasonable (which is not true for the full version).