UPDATE: Selected Tags to Lyrics v1.1
Primarily for iPhone and iPod touch users, Selected Tags to Lyrics will copy any combination of Name, Artist, Album, Grouping, Composer, BPM, Comment, (Long) Description, Year and/or Bit Rate tags to the Lyrics tag of the selected tracks, such that this info will be available with a tap when the track is playing. Can append to or replace current Lyrics info.
Latest version accounts for description and long description, preferring the latter, and adds "year" and "bit rate" as options