It’s not as cool as sketch mode in ZB, I know. But I have to use Photoshop, a lot. So I keep developing this thing. Any way, as ZBC is the only forum I frequent, you’re all artists, and many of you probably have PS, you get the exclusive post 
Major improvements including a one-click sketch book canvas, one-click complimentary color bar, and rebuilt-from-scratch tools equate to an even more authentical-like experience.
Pretty useful for sketching, rendering and texturing tasks.
Compatible with Adobe Photoshop CS4, on Mac and Windows.
More details and the d/l here: http://nkurence.com/blog/2010/01/nks3/
Enjoy~

maybe a cs5 upgrade (last chance for me, i guess) anyway,