Idea: to reduce littering in ATMs

Switch banks. Go to one that will e-mail you a receipt as an option and learns your preferences for frequently-accessed options. "Deposit check, mail me the receipt with images". "Withdraw $40 cash, mail me the receipt". Both are buttons I can get right on the PIN screen.

Yep, instead of hitting OK, I can just tap a button which will log me in, do the transaction, spit out the card, and do whatever I asked it to do.