There's also "Phone-omenon" by Doug McKenzie, with which you can "cause any prediction to appear on a stranger's cell phone." I believe that David Blaine performed it on one of his many TV specials.
Here a description of an effect -- "A random stranger in the crowd is focused on remembering a card when suddenly her cell phone rings. She takes her phone out of her pocket to check who is calling only to see the name of her card staring her in the face."
I don't have it, and therefore cannot recommend it, but it sounds dynamic.
It's okay. But if you're expecting anything breakthrough, prepare for disappointment.
Something I do all the time is if someone leaves their phone out and forgets about it, I take a picture of a playing card (in some dim, eerie lighting helps add to the effect) and set it as their background image. Then I leave it out for them to find and hopefully they'll just stick it back in their pocket if they see it lying around (I keep an eye on the person, though, because if they open their phone, I can't perform the trick). Later I force them that card (if you've got a good one, mental forces add SO much to the effect!). Then, sometimes I just ask them to clear their mind and concentrate on their and, after building it up some more, ask them "Do you have a cell phone?". They take it out and flip out. Other times I tell them to take out their cell phone and hold it tightly between their hands,
then force them to card, then tell them to clear their mind and picture the face of their card. Then, after a bit of silence, I let them make the discovery.
It gets great reactions whenever I do it, and it's a quick trick that lets you focus on your presentation.