Why not have a crack at ombre nails? I am loving these impossible gradients with pastel colours and glitters. All you need is a few colours, a nail sponge to apply the second colour and some precision and patience!
In short, you do the base colour, let it dry and then sponge on the tip colour trying your best to blend the colours as neatly as you can.
Try blending oxblood or a rich aubergine colour with black to stay on trend with this seasons gothic edge, or more neutral colours and glamourous glitters to keep it sophisticated.
You can also try ombre nails fading gradually from one nail to the next (like below), which might better suit someone who wants to get the look but doesn't have the time, and anyone who has a huge nail polish collection!
(Images, in order, from originalpiecemag.com, elleandblair.com and imagesforfree.org)