MusaTagger is a very complete tag editor, supporting most of the features of id3v2. It is built on GTK+ 2.0, and it supports automated renaming of the songs, tagging multiple files at a time, play counting and rating, as well as the more basic features any decent tagger should have. MusaTagger is a part of Musa, which will be a full-featured jukebox for Linux.
PodAdmin is a very simple Web-based podcast management tool. When you upload your new episode via a Web form, PodAdmin will grab the title and description from the ID3 tags and generate a new RSS feed on your Web site. Optionally, you can specify the title and description, if it is not embedded in your audio file.
Menu Buddy currently comprises a couple of Python scripts for creating GNOME panel menus from a directory hierarchy of music files. These menus can be used to play or enqueue songs in XMMS, as well as pause or skip XMMS. These scripts are not terribly powerful yet, but there is potential for a signficantly more flexible system of menu-creation that allows automatic construction of many different kinds of menus based on directory hierarchies.