This might seem like a small thing; it's in the drawer for a reason, but it is one of my favorite effects and one I would perform for any gathering, from an impromptu performance when someone at the table asks me about mentalism to a full-on stage show.
The core method is versatile; it can be applied to a lot of classic mentalism plots (it is my favorite method for Kurotsuke type of effects) but also impromptu (I can literally grab some business cards and perform this effect on the spot). It is cheap (that kind of goes hand in hand with the impromptu part) and technically easy (which means that you are free to focus on the presentation).
But, to be fair, I have had this method in hand for a long time. It is this particular presentation that got me to get it out and perform the effect. This is a lot of fun to perform and, if you have the right persona, it gives you a perfect excuse to let your personality shine early on in a show.
Get it, learn the presentation, take it out for dinner, buy it a drink, realize that this is not just a fling, and who knows… you might end up married to this effect!