Well, I'm still really wet behind the ears when it comes to this business, but to me what'll do well with .biz are true generics (like cellservice.biz -- seems good to me). Industry names, keywords etc. that would appeal to a broad audience. There have been some .biz names selling fairly well recently (one generic .biz went for $500 or $600 recently on Afternic I think).
My opinion is that it's shortsighted to declare .biz dead already. Is it going to sell for a lot of money in the short term? Probably not. I tend to think of good generic .biz domains as a longer-term investment. Some risk, of course, since the market for .biz hasn't been made clear yet, but this entire business is pretty high risk.
Just my opinion,
ripley.