Dude,
I'm sorry to say that I haven't seen a good hovercard gimmicked or not, but look here if that's what you mean. You might mean a levitating or floating card. And, I'm sorry to say it, there is a tutorial on youtube. Just search for it. Hope that helps.
The name of daniel garcias impromptu haunted deck escapes me, but thats pretty good too. when its rising/coming out of the deck its shown fair on all sides.
I think the best one is the standard rising card gimmicked deck that can be found just about everywhere. I've yet to see an impromptu rising card that looks anywhere near as good.
The best in my opinion is the one thats in Jay Sankey's revolutionary card magic because you dont have to buy any gaffed decks and you can make your own gimmick, and its pretty clever.