One-key chording

Hello. Does anyone know of a software instrument or other way to play entire chords with one keystroke on a usb midi keyboard or the onscreen keyboard? I see that the iPad version of Garageband has "smart" instruments that do this. Is there a way to do this on the full, Mac version of Garageband?

I don't think there is any feature in Garageband that can do that. But you can use a plugin in Garageband to do this.

I found this will browsing Google. Maybe this will help you. Make sure you install the Audio Unit not the VST, as Garageband cannot read VST's only Audio Units.

http://www.everythingableton.com/2011/01/free-audio-plugin-of-the-week-12/