Cult Nails currently has what they're calling 'Convert Packs' for sale. They consist of 2 polishes meant to be layered together and Wicked Fast top coat. I purchased #4 a few weeks ago and am blown away by the beauty of Seduction layered over Time Traveler.
These photos show 1 coat of Time Traveler, a rich dark navy cream - a perfect blue in my opinion - with 2 coats of Seduction.
On a slightly related note I am thinking of attempting to fix my broken nail with tips and gel polish as seen in a tutorial on The Polished Mommy. Has anyone else used this or a similar technique and if so what were your results?