I call this a "lazy" ombre mani because I just did all different shades of blue shimmer polish on each nail, not a true ombre where the polish transitions from dark to light on each nail. But I think it still came out cool and I'm enjoying wearing it right now.
This mani is OPI Russian Navy on my thumb, Lancome Indigo Paris on my pointer, China Glaze Blue Paradise on my middle, China Glaze Frostbite on my ring finger, and Sally Hansen Salon Calypso Blue on my pinkie finger. OPI Ink is a good substitute for Lancome Indigo Paris. I think these manis work best when you keep all of the polishes in a similar finish (i.e. all cremes, or all shimmers/pearls like I did).
I also think that ombre manis are a cool way to move from wearing summer polishes to winter. Right now, I'm trying to hold onto the last bits of summer, so I'm not ready to rock dark nails. This way, I have dark nails mixed in with some summery colors!