Marketing your digital library often takes creativity. Although a digital library is in the ether, you need to reach out and touch your users (your public). The Liverpool (NY) Public Library has been doing an interesting marketing/outreach activity. They've been going to a local hotspot (food-wise and with wireless access) to answer reference questions, register people for a drawing of library-related stuff and sign people up for library cards! You can read a brief posting about it here.
Are you reaching out and touching your public? Doing something creative? Write a comment to this post and tell us what you're doing!