Like Mitchell said, my little mind often needs airing out. No thoughts of any PS manipulations, etc. I love to hike and boulder hop. I'll take my dogs to the mountains or something like that and we'll play in nice clean air with nobody around. It does open my mind for ideas later. I also sometimes just take a vacation from PS - though that's difficult for a shopping addict!
Sometimes I'll work around a theme of interest, like my sisters inspired "modern madonna." I did a series based on songs that now and then run through my head (helps to exorcise them, lol). I definitely agree with fatboy. I use deviantarts for a majority of my Photoshop work. I'll go through, find artists I like, go to their galleries, and download a bunch of images to a folder with their name. Later I can go to those images and start to get ideas and put them together, maybe go searching for more to experiment with for the idea. I will on occasion open my fine art books and look at the artwork for ideas. Of course if you're a photographer or simply like to snap pics, there is a world of inspiration to be found there.
Whatever I do, I make it something of interest to me, a fantasy, a love, a hobby, the kind of reading I like, things like that.
Inspiration can't be forced, but there might be a 900 find ur muse line!
