In reply to this thread, I would say the best and easy card magic effect is "Easy estimation aces by Paul gordon". Just set the aces up in order beforehand and false shuffles and cuts before you begin to cut to the aces. That way you don't have to do a faro shuffle. Really great effect in my opinion, I've been performing this in quite a while.
Also, another card effect you might want to check out is "Fully Automatic Card Trick" by Caleb Wiles, it's completely self working and the spectator does all of the work.
If you're looking for impromptu then look no further than "Dai vernon's Triumph", "The Biddle Trick", also check out moment's notice pdf book series by Cameron Francis, all of these effects are using cards and all are impromptu. I've been using a few of them in my walkaround gigs for about 8 months now. well worth looking in to. I hope this helps!