+1 here too. I use BeaTunes to find the key but it can be done using half a dozen other offline tools.
What I would like is not just the key of the current song but also a key column to sort by.. Right now I copy all my keys to the Grouping tag and sort by that - but I'd prefer to just read the KEY tag for keys.

OTOH - the idea of a toggle-able key display for current tracks on each deck suits me better than one that's there all the time. I LIKE the current interface of CrossDJ - but it is a bit cluttered looking - especially to newer DJs. The look of DJay is more accessible to most. What I love about Cross is that a ux is modular. And I only need to know they key once....
So specifically what I'd like is to be able to click on the title of the current track and have that title replaced with relevant info for as long as the button is pressed. Once I have the info in my head (2 secs tops), I can just move on.
Thanks!
Frank.