Hyper’s CD Catalogizer (short name: cdcat) is a GUI disk cataloging application. It can catalog CDs, DVDs, and other removable storage files, and also regular directories and files including your downloads.
It is using the Qt toolkit so it probably look best on KDE, but it works perfectly on GNOME. The user interface is pretty and straightforward. Easy to use too. There aren’t many options but it does its job very well. Searches are fast, at least in my computer and catalogs.