The first is a Pinterest Party. I saw this idea on a blogger's instagram (PSST--follow me @sotomorrow). Her library invited people to come and do a show and tell of projects they had completed based on ideas from pins. You could also pick 3-5 quick, fun projects and set them up as stations, depending on how much room and time you have. If anyone reading this works at the Palo Alto Library (or another one that has done this), I'd love to hear how it went. A bunch of my regular patrons/moms are on Pinterest (and following me, so I am trying to behave, ha!) and it would be fun to get them all together and craft.
Another is a young adult book club for people who aren't teenagers anymore. When I lived in Grand Rapids, I attended a book club like this and, while there was never a crowd, it was a lot of fun. Many book clubs in libraries seem to be aimed at people who are 50+, and I can understand that it's hard to get anyone younger, but I think we have a bit of a self-defeating prophecy sometimes here too.
What about a class on baby bargains? You could cover breastfeeding, cloth diapering, couponing, products it's safe to get secondhand, etc. Women, Infants, and Children (WIC) provide free lactation counseling to qualifying participants. If you have a cloth diaper store in your area, perhaps the owner would be willing to bring some samples in.
A related idea would be a workshop on photographing children for parents, grandparents, and other relatives. Professional photographs are expensive. I'm glad that we were able to hire our wedding photographer to shoot photos of our daughter as a newborn, but many people aren't so lucky.
What are your dream library programs for younger adults? Or is your library already targeting this age group? I put a call for program suggestions for this age group on Twitter and here were some of the suggestions: