Recently I came across very useful yet very simple application to create patterns from every image you upload to it. It's quite fun, a bit like looking through kaleidoscope when searching for a pattern you like. It's called Repper pro. Check this short video that shows the possibilities of this app.
I bought the full version of course (29EUR). Check their website: http://repperpatterns.com/ . And here are some cool stuff I've been able to create with it.