A good annotation can contain one or several of the following:

• Sample identification
• Reference or allusion identification
• Artist explanation
• Slang decoding
• Relevant image
• Literary terms
• Themes
• Reaction
• Joke
• Producer tag
• Translation
• Alternate lyrics
• Uncertain lyrics
• Question
• Something creative!

Separated miscellaneous stuff for now:

• Header
• Produced By
• Cover art