MusicBrainz Picard is a cross platform application that has been written in Python. It is the official MusicBrainz tagger software. Picard supports the majority of audio file formats, and is capable of using audio fingerprints (AcoustIDs), performing CD lookups, and has excellent Unicode support. Furthermore, there are several downloadable plugins that extend the features of this app. Picard uses an album-oriented approach to tag files, allowing it to utilize MusicBrainz data effectively. Picard was named after Captain Jean-Luc Picard from Star Trek.
Mp3tag is a great and easy-to-use freeware tool to edit metadata of common audio formats. It supports ID3v1, ID2v2.3, ID3v2.4, iTunes MP4, WMA, Vorbis comments and APE tags. It works by renaming files based on tag information, replaces characters/words in tags and filenames, import/exports tag information, creates playlists and lot more. It also supports online database lookups from sites like Amazon, discogs or freedb, allowing you to by design gather proper tags and cover art for your music collection.
Tigo Tago is a spreadsheet based tag editor for media files. This enables you to easily set and modify tags, and to rename a huge number of files at one time. The convenient multi-selection feature of Tigo Tago allows for flexible mass tagging and mass renaming operations. The user has full control, and all changes are previewed before they are saved to disk. With Tigo Tago, no typing is needed while filling tags, since they can also be imported from freedb or discogs.