So, I may be tardy to this party but I just noticed Lauren Conrad's nails in this photo and I love the concept! Apparently it's something referred to as Ombre Nails. The whole concept is simple – paint each nail a slightly darker colour while staying in the same colour family.
If you do your own nails though, this means having a colossal amount of nail polish. I think this is a look better left for the pros and I might attempt it before the summer colour season is over!