The end of Bleach episode 123, where Ichigo is fighting against his Hollow self to decide which one will control the whole body. In this part Ichigo learns that his Hollow self is capable of doing Bankai too. Pretty cool episode and great ending.
definitely my favorite cliffhanger in the entire series. do have to admit; Hollow Ichigo's a pure badass being able to maintain the insane smile even when yelling "BANKAI!"