I like the idea of one of Urahara's inventions taking out Ichigo's hollow. The hollow could even be he villain of the arc- Ichigo has to hunt it down and get it back into him using a different invention of Urahara's.

It could also be a little bit more...technical. Internet leak. Word of Soul Society and Hueco Mundo is leaked due to a post in an internet forum. I don't know where we'd go from there...some insane exiled shinigami deciding the world needed to know? At the end people could have their memories wiped via a handy little web page and some creepy otherworldy technology. xD

Erm, we can always come up with new races. There were some pretty interesting ones near the beginning of the RP OOC, like shinigami from Hel who work to condemn souls.