Tonight's nail art comes straight off of ColourLovers. It's a gorgeous gradient, but it's called melting. It actually looks like it is melting, and so do my nails.
The colors used were Load (Illamasqua), Rock-a-Guy Blue and Blue Sky's the Limit (Sation).
This was a really easy design to do. Just paint your base color, add messy stripes of your second color about half way down your nail, and then add some more on top of that near the top of the nail. Easy and effortless.
EDIT: 8/26/12 You can easily try this yourself. Follow this new tutorial for the exact steps and tools you'll need.