Here is the full list of all 18 Karaoke Revolution: Glee Volume 3 achievements worth 1,000 gamerscore.
Get 100% on any song on any difficulty
Get 1,000,000 points or more on a single song
Get a streak of 40 or better on a single song
Sing a song with two players in Versus mode
Sing a song with two players in Co-Op mode
Sing a song with two players in Duet mode
Get 95% or better on "Don't Go Breaking My Heart", "Go Your Own Way", and "Last Christmas"
Get 95% or better on "I've Gotta Be Me", "Just The Way You Are", and "Losing My Religion"
Get 95% or better on "Back To Black", "Songbird", and "Valerie"
Get 95% or better on "Fat Bottomed Girls", and "Only The Good Die Young"
Get 95% or better on "I Look To You", and "River Deep Mountain High"
Get 95% or better on "Never Going Back Again", and "PYT"
Get 95% or better on "I've Had The Time of My Life", and "Lucky"
Earn all snapshots from a single song in YEARBOOK mode
Play every song in the game at least once on any difficulty
Earn 10,000 or more dancers lifetime
Earn every snapshot in the game from YEARBOOK mode
Get 100% on every song