Hmm...
A simple sandwich effect such as FISH SANDWICH (Oz Pearlman) is so easy, but so effective. A quick force, and a mind reading revelation would also be quite good. Another thing you could do is just select a card, do a pass, and do a color change, yes, it get's great reactions (shapeshifter, classic color change...etc.).
I am not sure if a 2 card monte would fit under this category, but it is a great one to try. Anything from TRILOGY DISC 1 could also be a good option. Especially Hand to Mouth and SUBWAY.
Hopefully this helped!
Good luck,
-Sanj
EDIT: Iron Fist is what I believe the guy above me is talking about. Also, Chris Kenner's 1on1's such as Invisible Reverse, or Simple/Sloppy shuffle triumph are also wonderful. Pick up his book Totally Out of Control for some great effects that are indeed, short and sweet.