Calibre is an open source e-book management application. It has a cornucopia of features. Read more
EagleData is a database to export data as HTML tables or print labels.
fennel DVDManager (aka fsDM) is a DVD manager. Features include: Retrieval of DVD details from online site, creating box sets and wish lists, exporting a list of your DVD library, and more.
(shareware) Music Box is a handy database for your music files. If you have a large collection of them, it will help you to organize and keep them in order.
Norrkross Register is used to keep track of things like DVD movies, addresses, book collections etc. It is designed to be very simple and have a minimum of configuration.
Zittergie's Coin Catalog
Zittergie's Coin Catalog is a multi-platform coin cataloging software that featres Belgian, British, and Canadian coin catalogs, search functionality, and make your own collections.