Frosted hair was really popular in the '80s. It's very much like highlights, but the affected hair shines with a grayish tone. I like to think about it as malted locks -- like a malted milk ball or milkshake, there's a light dusting of silvery residue over your blondish strands. I think the most beautiful example is Debbie Harry when she's not a total peroxide blond.
This look went the way of the perm in the mid-90s, but I say it's time to bring it back. Unlike the big-hair fest that is the permanent, frosting is a nice alternative to brassy highlights.
True brunettes, watch out -- frosting looks best on natural blond or dishwater brown hair.