This photograph shows some of the consultation done by Hennepin County Library during the US National Library Week. You can see more images at this link.
I really like this, and it is a great way to find out how people who use the library think about it.
Another part of this could be taking similar questions to the local park, the farmers markets, and other areas where people who use your library could be. This could be a way to reach people who use your online resources, but don't go into the buildings. It could also be a way to let people who don't use your library know about what could be in it for them.