Akio123 said:
The shibas aren't a noble family to my knowledeg.
They aren't anymore, but they were at one point. They're sort of a disgraced noble family now.
Renji said:
There are more people with Nakai then you said Lucy.
Mayuri, Genryuusai & Kaname also have Ban-kai's. And we have seen them all too.
Genryuusai has not revealed his Bankai; believe it not, that was only his SHIKAI that he revealed in the battle against Ukitake and Shunsui. There have been 8 Bankai's revealed, and they are (in order of appearance):
Konjiki Ashisogi Jizou: Kurotsuchi Mayuri, revealed as a last resort during his battle against Ishida Uryuu (ch.125/ep.44)
Hihiou Zabimaru: Abarai Renji, revealed during his battle against Kuchiki Byakuya en route to Soukyoku Hill (ch.141/ep.52)
Senbonzakura Kageyoshi/Senkei S-K/Shuukei: Hakuteiken: Kuchiki Byakuya, revealed in an attempt to prevent Abarai Renji from reaching Soukyoku Hill, with subsequent abilities revealed during his battle against Kurosaki Ichigo atop Soukyoku Hill (ch.142/ep.52, ch.166/ep.59)
Suzumushi Tsuishiki--Enma Koorougi: Kaname Tousen, revealed in a vain attempt to counter Zaraki Kenpachi's insane strength (ch.146/ep.53)
Kokujou Tengen Myouou: Komamura Sajin, revealed to carry on the battle that Kaname Tousen lost against Zaraki Kenpachi (ch.148/ep.53)
Tensa Zangetsu: Kurosaki Ichigo, revealed during his fight against Kuchiki Byakuya on Soukyoku Hill (ch.162/ep.58)
Daiguren Hyourinmaru: Hitsugaya Toushirou, revealed during an enraged attack against Aizen Sousuke (ch.170/ep.60)
Ryuumon Houzukimaru: Madarame Ikkaku, reluctantly revealed in order to defeat the 13th Arrancar Eduardo Leones (ch.205)
I'm fairly certain that's all of them.