Batch operations are missing,such as merging release-group in a raw by selecting each one and clicking on "Merge selected release-groups":
see http://musicbrainz.org/artist/20949b43-f5e2-4cc8-b33d-f68c0cc637e6.html

Or batch edit:
see http://musicbrainz.org/release-group/1210ef46-b745-4116-b84a-636808a1a697.html

Extending batch merge to all entities: release-group, release, recording and work is IMO required to ease the post NGS cleanup work.