mu is a collection of utilities for maildirs, in particular for indexing and searching them. mu fills a database with information about your emails, which can then be queried using an easy query language. It can work stand-alone or be integrated with a mail client. It also provides an emacs-based email client ("mu4e") and bindings for Guile/Scheme.
spuug is a little tool that generates the boilerplate code for GObjects. spuug can be used for "plain" GObjects, but also for more sophisticated objects such as GTK+ widgets. It tries to be a bit smart with the code in spits out. However, understanding of GObjects/GtkWidgets is recommended.