My list:
1. Martha My Dear
2. Rocky Raccoon
3. The Continuing Story of Bungalow Bill (Incidentally, if I were to judge from what few Yoko performances I've heard, I'd say she's singing awfully intentionally, for character effect. Her singing on "Happy Christmas (War is Over)" indicates to me that while her voice isn't exactly angelic, it's still much better than she lets on in this song. Assuming that's her leading the choir, that is. If that's someone else and she's singing a different part that I didn't notice, do tell me so I can listen more closely. If I hear a few songs where Yoko sings lead and remember this thread, I may change my tune at some point. Anyway, I find her part in the song to be rather entertaining.)
4. Dear Prudence
5. Sexy Sadie
6. Julia