The best nominations twist ever in my opinion is the one in BB6, the lie week. It was great

Or maybe (it's a bit of crap idea haha!) but maybe they could do a task or something, and the winner of the task is like the key housemate (or whatever). They then do nominations, and then everybody who nominates this key housemate faces eviction with the two that got nominated anyway.
Wow that's an awful idea but I'm proud of it hehe!
I like the lie idea from BB6, one week before the final BB could just lie about who's up, stage a fake Save and Replace, and then they only find out via Davina before one is evicted