The DIY Approach
Learning the skills on your own is a nice option, if you have copious amounts of free time after your work shift (or, for most people not holding a degreed job, shifts) to teach yourself the material, and then go out and find good-looking projects that need development in the skills that you're trying to level up that also have a robust mentor community or a really friendly developer community that doesn't mind taking new people in and letting them whack at things until they get it to work correctly, then elegantly, then according to the style and design of the project. Subscribing to mailing lists like code4lib and reading their work may be a start, but a lot of what goes on there is systems work, useful to people who are in the business of indexing, cataloging, and building code that allows for finding and discovering of the elements in the collections. There are conference announcements, and a jobs list, but to fully understand code4lib, you're probably going to be in a specific segment of library work. There aren't a whole lot of threads on the mailing list about people making small code releases that perform specific functions or make one aspect of library life better, or even that are just an entertaining diversion that got created in a program somewhere.