I'm a bit of a traditionalist when it comes to the ambitious card. My favourite presentations for the ambitious card have always been the simplest:
-Tommy Wonder: The card rises because you chose it and made it special
-Daryl: a demonstration of magical card control.

Other presentations like the yeast card or the remote control card, though original and creative, have always seemed a bit goofy to me. (But that's just me.)

I like to use the plot of a ghost card that keeps hunting me

The most logical patter I've come up with is that you have the ability to control the card, and show how the dealer can cheat with this technique.

Tell them to choose a card that has significant value, some people like Aces. Have them sign it. Stick it in the deck anywhere, completely lost. Say that you don't know where it is, but if you flick your wrist (or snap(, it comes to the top. Then you can take that card, and deal it to your partner.

I like to use Greg Wilson's "time machine" ruse, in which he refers to his watch as a time machine and so everytime he places the card down in the deck, he proceeds to push the "time machine" button and thus we go back in time 10 seconds to when it was on top. The routine that this idea is from, Flashback, builds until he actually ends up sending the entire deck back in time to when it was a new deck out of the box in original deck order. I just use the idea of a time machine, and the comedy that's inherent within it.

Most of the time, I don't refer to the card as anything in particular. I would never call it "The Ambitious Card" to a lay audience. I also wouldn't call it the Yeast card or the Ghost card or the uppity card or anything else. I use the ACR in combination with Solid Deception (which I also do not refer to by name) as a lead in to the Card in Wallet.

I usually call it the Two of Spades trick (or whatever the card happens to be). You don't need to call a trick by any particular name.

The reason it keeps coming to the top, is that I riffle the cards. That makes the card move.

I love forcing the card, and letting them sign it while my back is turned.
While they're signing I explain that there is 1 card in each deck that does strange things.. I say that in this deck it's the _____ (forced card), they start smiling and say it's their card.. I turn back to them and say: "well... you've already signed it, so I'll try doing the trick anywhere.. hope there won't be any problems".
I place the card in the middle, and I say: "the card is not on the bottom, and not on the top..." when I turn the top card over it's their card, and I just do it again and again..
Works for me...

Tomer