I knew exactly where to turn for this challenge: to Disneyland! More specifically, to the nail polish set I bought when I went to Disneyland last year - the Wickedly Beautiful set. (I note that it's gone up $5 since I bought it, so I feel like I got a retrospective bargain.) Disney has a make-up range called Beautifully Disney, and one of the their nail polish sets is for the "wonderfully wicked ladies", or evil villains. There's Mistress of Evil (Maleficent from Sleeping Beauty), Midnight Hour (from Cinderella), Just One Bite (the Evil Queen from Snow White), and the polish I used, Diva of the Deep for Ursula (from The Little Mermaid).
Diva of the Deep is a lovely dark purple with a warm reddish shimmer through it. Application of the polish was excellent, although it dried with a rather dusty finish - a bit of topcoat fixed that right up.
Since this manicure is all about Ursula, I then stamped tentacles on using Bundle Monster plate BM-401, which is much better etched and was much easier to stamp with. I love Ursula and she certainly owns the stage with her tentacles!
And here are some shots of the whole collection and its packaging. Check out how cute the bottle tops are! They also lined up with the bottle so the image faces you along with the logo - great attention to detail.