ID3 editor which can pick data from internet

Metadatics is the most similar to, though it isn't free. But it's pretty great.

Nothing (on any platform) is quite as comprehensive as mp3tag.

 

Here you go: http://musicbrainz.org/doc/MusicBrainz_Picard

Bit of a learning curve, but worth the effort.

The blurb says: "Picard supports the majority of audio file formats, is capable of using audio fingerprints (AcoustIDs), performing CD lookups and disc ID submissions, and it has excellent Unicode support. Additionally, there are several plugins available that extend Picard's features.

When tagging files, Picard uses an album-oriented approach. This approach allows it to utilize the MusicBrainz data as effectively as possible and correctly tag your music."

(Windows, OS-X, linux and source available..)