Another very helpful trick is to use AppleScript if you're on a Mac. Someone here -I always forget his name! Shame on me!- posted his code some years back. And thanks to it, I just pick a colour in Photoshop and Ctrl-C and the colour is created in Quark.
Let us know if ever you're intersted in that script.
EDIT: Of course this is still not the simple tool you're requesting. I'm totally with you to beg such a “simple” tool.
Jean-Marie Schwartz
> Mac Pro Quad Core Intel 2.8 GHz, OS X.6.8, Quark XPress 9.2, Adobe CS5 <