Adding a transmog system would be a great start to keeping things 'unique' (although there are a few that have it already). The biggest issue really is coming up with something that can make us apart from all the other droves of WotLK servers that run the fully optimized and updated Trinity branch. I agree that customs added a special flavor to NE that I always enjoyed, even when I had first joined the server years ago I loved the idea, even if they where incredibly OP. I've always been interested in a fun server, like the ones that used to be popular circa '08. However I've made one my self and the amount of work and time that goes into making something like that stable and "balanced" is insane.
As I am already playing retail at the moment, playing another fully "blizz-like" server would almost be redundant in a way. I would enjoy it for the most part as I would hopefully be playing with my old friends, but at the same time the content would get stale for me, and I feel for others as well. There's only so much ICC I can take. Sure there's PvP and that usually last a while, it was the main focus of NE for the most part.
I don't know, coming up with truly unique ideas while having to stay within the confines of being "blizz-like" feels difficult. We have to think in terms of "How can we show and prove that not only do we have the best core WotLK server, but also have the most exciting,unique, attractive content to offer." Staying open and positively cautious to new ideas is the best we can do right now. It's a seriously precarious situation the server is in right now.
I have hopes for NE's return, and I believe it can be done, but we need to stay realistic in our expectations. We can't just put on those rose tinted goggles and ogle at the past. The most important thing to do here is look towards the future and what we can do to improve on the past server we all loved so much.
The one thing you have going for you right now, is that many servers are pretty bland.