The organisers of DISC 2014 had a great innovation that I have not seen in any other conference:
At the registration desk, you just pick up your name tag.
That's it. You don't get a conference bag (you have a bag with you anyway). You don't get a printed copy of your receipt (you already got a receipt when you did the registration online). You don't get a paper copy of the proceedings (it's available online for download). You don't get gifts, pens, notepads, advertisements of book publishers, or the annual report of the local university. In general, you don't get anything that you would just throw away.
(For convenience, some paper copies of the conference program and some USB sticks with the proceedings book are available.)
This is very easy for both the conference organisers and the participants. No extra things to carry around. No pointless waste. Great idea, many thanks to the local organisers!