Tama's suggestion:
H!P's Best Abs Ranking
(Um, I don't really remember most people's abs, sorry)
1. Rika Ishikawa
2. Erika Miyoshi
3. Eri Kamei
4. Maki Goto
5. Makoto Ogawa (well, I remember seeing her around the Koharu concert and being impressed, so I'll give her props for that)