What tricks can I use to add value to my poster? Going round conference poster sessions, I notice the occasional poster where the presenter has used a bit of creativity to help with their communication/networking, perhaps related to linking in some way to online information, or giving people something to take away that will help them to remember the person or information. What methods have you used or come across that add value to a poster in that sort of way?

I'm interested in things outside of the basic content of the poster - by "basic content" I mean the text and images that communicate your research (there are some good answers to this question that cover that kind of thing).
Trying to avoid basic content organization that is already mentioned by this question.

From the added values point of view, I have seen/would have appreciated:


option to take a print-out with an abstract, arXiv/full paper that the poster is based on
have business cards ready/available to be freely taken (you might have to be creative on how to attach/arrange things around your poster/poster board depending on conference organization)
QR code in the poster with a link to a relevant website (source code, open data, etc). I tend to take pictures of posters that I am interested in. And I like QR codes. 
have a note (somewhere visible) that you will be available (and be there!) in the coffee shop of the conference location at a specified time if somebody wishes to discuss the research. Reason: sometimes you are presenting research that attracts a lot of people, so you are always busy talking and presenting. So, not everyone gets a chance to talk to you – and their time near the poster is also limited, so they might not come by around the second time - only to find you busy with another person questioning you on some irrelevant topic.
If you are presenting something for which "you can print a simplified 3-D model", not necessarily up-to-scale - that is always fun.


I do not mention the "freebies" that you can giveaway without creating obstruction since they might attract people to your poster but probably will not add value. However, certainly, have them if you can :) I would not complain. Nobody would complain.