Kid3 is a nice KDE application, which recently reached version 1.0. It allows you to edit the tags of all major audio formats, like OGG Vorbis, MP3, FLAC, MP4/AAC or WavPack.
A usual instance of Kid3, editing OGG Vorbis tags (click to enlarge)
The best feature Kid3 ships with is the ability to edit multiple files at the same time, somehow similar with the way Amarok allows you to edit the tags. You can select all the audio files in a directory and change the editable tags by filling the fields only once, then save the modified files.
Editing tags for all the FLAC files in a directory
The configuration dialogue includes the possibility to set the text encoding for tags or to select which version of id3 tag will be used for MP3 files (2.3.0 or 2.4.0). You can also set Kid3 to automatically replace non-English characters with standard ones.
Kid3 is lightweight and fast, and is perfect for editing any kind of audio file, taking advantage of an efficient way of doing it.