As someone who has trained in hypnosis and NLP I know how effective visualisation can be. It's a really cool tool that can teach the brain to look for new things unconsciously and can help you improve your life. What 'The Secret" does, however, is tell you that you can visualise ANYTHING and have it come to you and I've long thought that to be rather misleading.
Today, I put it to the test. I found something I really, really wanted and was clear about when I wanted this thing. I even used Twitter to help me. I asked "The Universe" for a really hot guy to tweet me within 15 minutes. I focussed on this with great intensity - well, there was a hottie at stake after all.
15 minutes later - no hottie.
Don't get me wrong, visualisation is GREAT but, like any tool, it won't work for everything and the only "universe" your thoughts control, in my opinion, is your inner universe.
My conclusion is that the basic premise of "The Secret" appears to be flawed... and possibly that I have no hot friends on Twitter!