vvvP (Virtual Volumes View Photo Edition) catalogs photographs on removable devices and hard disks at the same time. Images can also be arranged in a single virtual filesystem. Each folder of this filesystem can contain images from many disks. The program allows you to view image thumbnails and full images.
The cdcat is a graphical (Qt based) multi-platform catalog program that scans the directories/drives you want and memorizes the filesystem (including the tags of MP3s) and stores it in a small file. The database is stored in a gzipped XML format, so you can hack it, or use it if necessary. Cdcat can store the contents of some specified files up to a size limit if you want (for example: *.nfo).