Everytime I see Robin Moses doing rainbows I feel like doing rainbows. She always does them in this way, spearing the rainbowness accross all nails. They're so fun and happy. Plus I get to use a sponge, which I love doing.
The one above was included on my favourites post.
The second one is also shimmery. I honestly don't remember which nail polishes I used for any of these, so we'll try that next time.