Here's what I've done. If it's a good effect that already exists, than there's a gaurantee someone somewhere has a video of themselves doing it on Youtube. So start there by typing in all the keywords that relate to your effect, & see if you see anything simlar to what you have. If you cant find your idea, than the next step is to Google it, again to see if it has already been created. Than finally, post a detailed description of the effect on all the magic forums, but without revealing the method (in case it is original), & ask all the magicians if they have ever seen or are aware of an existing effect that's simlar to the effect you described. If so, than research it. If no one has, chances are you might be on to something. Than to double make sure, just like RDChopper said, ask Jason England, &/or any other magician who has an expert knowlegde of card magic.