I recently had the pleasure of exploring various approaches of Spot Varnish on my Cycles & Seasons 2011 Series. Here are a couple examples of the Color Art + Spot Gloss. View Slideshow of all 12.
Instead of pulling direct shapes and hues from the color artworks for the clear coat, I intentionally made it interact in different ways. Some play with the initial form and others completely break the rhythm. It's fun when a shape gets varnish on part of it and ends up having multiple saturations of the original color.
Spot Varnish is one of those things that can really make a printed piece jump off the page. It costs more and takes a bit longer at the press, but it is definitely worth it in the end.
The result is hologram-esk depending on the light source and angle viewed. Check out the full series Here.